feat: 移除 Codex Fast mode 与 AutoReview 后台分析，模型改为配置驱动

移除 pi-extension-codex-fast-mode：
- 删除整个扩展目录；同步清理根 package.json 的 files / pi.extensions /
  dependencies 条目、package-lock.json、tests/extension-load.test.ts 断言
  与文档章节。
- pi-minimal-footer 的 Fast on 渲染是该扩展的唯一消费者。扩展移除后 accent
  分支不再有生产者，collectFooterStatusItems 简化为直接返回非空状态字符串，
  去掉 FooterStatusItem 与 accent 标志，避免留下死代码。

移除 500 次裁决后的后台分析体系：
- 删除 analysis-agent.ts（192 行）与 ledger.ts（296 行），以及对应的
  auto-review-runtime / auto-review-ledger 测试。
- runtime.ts 由 177 行收敛到 85 行：安装选项缩为 { service, config }；删除
  handleAgentSettled 与 agent_settled 注册；保留 session_start / turn_start
  （denial circuit breaker 属安全语义）/ session_shutdown。
- 删除 analysis 配置键：config、extension-config、config-schema、生成的
  permissions.schema.json 与种子配置。
- 删除 reviewer 的 onDecision 回调（唯一消费者是 ledger）。
- 删除迁移机制 scripts/migrate-permission-policy.mjs、其测试与 update.sh 中
  46 行 migrate_permission_policy 接线。种子部署保持“目标缺失才写入”，已存在
  的 policy.jsonc 永不被覆盖。

AutoReview 模型改为纯配置驱动：
- 删除 DEFAULT_PROVIDER / DEFAULT_MODEL 常量与 findCodexTemplate 合成逻辑；
  model.ts 由 65 行收敛到 48 行。
- provider / model 任一缺失时返回新增失败类别 model-unconfigured 并 defer 到
  人工审批；provider 未注册或模型未发布同样 defer。
- reasoning 不再有默认常量，完全由配置决定。
- session_start 在 auto-review 已列入 authorizerChain 且 provider/model 未配齐
  时 ui.notify 提示一次，避免不使用 AutoReview 的用户被打扰。
- 种子 autoReview 只保留 enabled，provider/model/reasoning 由用户按本机实际
  可用的模型填写。

破坏性变更：analysis 键已从 strictObject schema 删除，任何仍带该键的
policy.jsonc 会使整份配置被拒（fail-closed 到全 ask）。这是刻意的变更，已由
config-loader 测试固定，防止将来无声放宽。

测试：
- 新增 auto-review-model.test.ts（7 例），覆盖此前完全缺失的模型解析：真实
  命中、未配置、provider 未知、模型未发布，以及不再合成替代模型。
- 重写 auto-review-runtime.test.ts（6 例）：authorizer 注册、未配置时提示
  一次、已配置 / disabled / 无 UI / 不在 chain 时静默。
- config-loader.test.ts 新增 2 例：带 analysis 的旧配置被拒且 fail-closed、
  autoReview 逐字段合并。
- composition-root.test.ts 的 EXPECTED_HANDLERS 移除 agent_settled。

文档：AGENTS.md、README.md、pi-permission-system 的 README / CHANGELOG /
configuration.md / architecture.md / auto-review UPSTREAM.md。

验证：pi-permission-system 的 typecheck、2577 个测试与 build 全部通过；根 50
个测试通过；schema 重新生成无漂移；新种子通过 schema 校验；5 个脚本 sh -n
通过；git diff --check 无空白问题。未安装 shellcheck；未执行真实 pi install /
update（属外部写操作）。

tests/extension-load.test.ts

@@ -43,10 +43,6 @@ test("all package extensions load together without global registration conflicts
 		packageJson.pi.extensions.includes("./pi-minimal-footer/index.ts"),
 		"the bundle must load the locally maintained minimal footer",
 	);
-	assert.ok(
-		packageJson.pi.extensions.includes("./pi-extension-codex-fast-mode/index.ts"),
-		"the bundle must load the locally maintained Codex Fast mode extension",
-	);
 	assert.equal(packageJson.dependencies["pi-compaction"], "file:./pi-compaction");
 	assert.ok(packageJson.files.includes("pi-compaction"), "the packed bundle must include maintained pi-compaction source");
 	assert.ok(
@@ -126,14 +122,6 @@ test("all package extensions load together without global registration conflicts
 			packageJson.pi.extensions.indexOf("./pi-tool-search/extensions/index.ts"),
 		"ask_user_question must register before Tool Search builds its catalog",
 	);
-	assert.equal(
-		packageJson.dependencies["@firstpick/pi-extension-codex-fast-mode"],
-		"file:./pi-extension-codex-fast-mode",
-	);
-	assert.ok(
-		packageJson.files.includes("pi-extension-codex-fast-mode"),
-		"the packed bundle must include the locally maintained Codex Fast mode source",
-	);
 	assert.ok(
 		packageJson.pi.extensions.includes("./pi-notify/src/index.ts"),
 		"the bundle must load the locally maintained Kitty notification extension",

tests/permission-policy-migration.test.ts

@@ -1,129 +0,0 @@
-import assert from "node:assert/strict";
-import { mkdtemp, readFile, readdir, rm, stat, writeFile } from "node:fs/promises";
-import { tmpdir } from "node:os";
-import { join } from "node:path";
-import test from "node:test";
-
-import {
-  LEGACY_PERMISSION_POLICY_HASHES,
-  migratePermissionPolicy,
-  permissionPolicySemanticHash,
-} from "../scripts/migrate-permission-policy.mjs";
-
-const knownLegacyHash =
-  "9abf020e80fceae8c52de3e8b758822dfc86cb90e9083381e2569dde1e29400a";
-
-async function fixture(t: test.TestContext) {
-  const directory = await mkdtemp(join(tmpdir(), "permission-policy-migration-"));
-  t.after(() => rm(directory, { recursive: true, force: true }));
-  const policyPath = join(directory, "policy.jsonc");
-  const seedPath = join(directory, "seed.jsonc");
-  const seed = `{
-  // bundled policy
-  "permission": {
-    "*": "ask",
-    "read": "allow"
-  }
-}\n`;
-  await writeFile(seedPath, seed, { mode: 0o600 });
-  return { directory, policyPath, seedPath, seed };
-}
-
-test("recognizes the exact previously installed policy snapshot", () => {
-  assert.equal(LEGACY_PERMISSION_POLICY_HASHES.has(knownLegacyHash), true);
-});
-
-test("semantic hashes ignore JSONC comments, whitespace, and object key order", () => {
-  const left = `{
-    // comment
-    "permission": { "read": "allow", "*": "ask" },
-    "analysis": { "enabled": true }
-  }`;
-  const right = `{"analysis":{"enabled":true},"permission":{"*":"ask","read":"allow"}}`;
-  assert.equal(permissionPolicySemanticHash(left), permissionPolicySemanticHash(right));
-});
-
-test("migrates only an exact legacy semantic snapshot and creates private files", async (t) => {
-  const { directory, policyPath, seedPath, seed } = await fixture(t);
-  const legacy = `{
-    // formatting does not matter
-    "permission": { "*": "allow", "path": { "**/.env": "deny" } }
-  }\n`;
-  await writeFile(policyPath, legacy, { mode: 0o644 });
-
-  const result = await migratePermissionPolicy(policyPath, seedPath, {
-    legacyHashes: new Set([permissionPolicySemanticHash(legacy)]),
-    now: new Date("2026-09-02T03:04:05.000Z"),
-  });
-
-  assert.equal(result.status, "migrated");
-  assert.equal(await readFile(policyPath, "utf8"), seed);
-  assert.equal((await stat(policyPath)).mode & 0o777, 0o600);
-  assert.ok(result.backupPath);
-  assert.equal(await readFile(result.backupPath!, "utf8"), legacy);
-  assert.equal((await stat(result.backupPath!)).mode & 0o777, 0o600);
-  assert.equal(
-    (await readdir(directory)).some((name) => name.includes(".tmp.")),
-    false,
-  );
-});
-
-test("preserves customized policy content", async (t) => {
-  const { policyPath, seedPath } = await fixture(t);
-  const custom = `{"permission":{"*":"deny"}}\n`;
-  await writeFile(policyPath, custom, { mode: 0o600 });
-
-  const result = await migratePermissionPolicy(policyPath, seedPath);
-
-  assert.deepEqual(result, { status: "custom" });
-  assert.equal(await readFile(policyPath, "utf8"), custom);
-});
-
-test("treats the bundled seed as current and repairs its mode", async (t) => {
-  const { policyPath, seedPath, seed } = await fixture(t);
-  await writeFile(policyPath, seed, { mode: 0o644 });
-
-  const result = await migratePermissionPolicy(policyPath, seedPath);
-
-  assert.deepEqual(result, { status: "current" });
-  assert.equal((await stat(policyPath)).mode & 0o777, 0o600);
-});
-
-test("returns missing without creating a policy", async (t) => {
-  const { policyPath, seedPath } = await fixture(t);
-  assert.deepEqual(await migratePermissionPolicy(policyPath, seedPath), {
-    status: "missing",
-  });
-});
-
-test("rejects invalid current JSONC without replacing it", async (t) => {
-  const { policyPath, seedPath } = await fixture(t);
-  const invalid = "{ invalid\n";
-  await writeFile(policyPath, invalid, { mode: 0o600 });
-
-  await assert.rejects(
-    migratePermissionPolicy(policyPath, seedPath),
-    /invalid JSONC/,
-  );
-  assert.equal(await readFile(policyPath, "utf8"), invalid);
-});
-
-test("aborts if the policy changes before commit", async (t) => {
-  const { directory, policyPath, seedPath } = await fixture(t);
-  const legacy = `{"permission":{"*":"allow"}}\n`;
-  const concurrent = `{"permission":{"*":"deny"}}\n`;
-  await writeFile(policyPath, legacy, { mode: 0o600 });
-
-  await assert.rejects(
-    migratePermissionPolicy(policyPath, seedPath, {
-      legacyHashes: new Set([permissionPolicySemanticHash(legacy)]),
-      beforeCommit: () => writeFile(policyPath, concurrent, "utf8"),
-    }),
-    /changed during migration/,
-  );
-
-  assert.equal(await readFile(policyPath, "utf8"), concurrent);
-  const entries = await readdir(directory);
-  assert.equal(entries.some((name) => name.includes(".bak.")), true);
-  assert.equal(entries.some((name) => name.includes(".tmp.")), false);
-});

tests/tool-search-settings-migration.test.ts

@@ -172,10 +172,6 @@ async function updateFixture(t: test.TestContext, piExitStatus = 0) {
     join(repositoryRoot, "config", "pi-permission-policy.jsonc"),
     join(updatedBundle, "config", "pi-permission-policy.jsonc"),
   );
-  await copyFile(
-    join(repositoryRoot, "scripts", "migrate-permission-policy.mjs"),
-    join(updatedBundle, "scripts", "migrate-permission-policy.mjs"),
-  );
   await writeFile(
     join(bin, "pi"),
     `#!/bin/sh\nprintf 'pi %s\\n' "$*" >> "$MOCK_PI_LOG"\nexit ${piExitStatus}\n`,