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）。

pi-permission-system/docs/architecture/architecture.md

@@ -496,7 +496,9 @@ Nothing constrains an `Authorizer` to be deterministic. `LocalUserAuthorizer` is
 
 This package now owns the default model reviewer as the named `auto-review` authorizer. It is still downstream of deterministic policy: only an ordinary `ask` enters the authorizer chain, and a hard-guard `deny` never reaches it. The reviewer returns `allow`, `deny`, or `defer`; only `defer` falls through to the terminal human authority. Its transcript boundary admits direct user messages and recognized non-cancelled structured answers, never assistant/tool/compaction content.
 
-The composition root registers the authorizer on the same `LocalPermissionsService` instance it publishes. `installBuiltinAutoReview()` returns lifecycle methods instead of registering a second set of Pi session handlers. The root's single `session_start` and `session_shutdown` handlers coordinate service publication and reviewer state; `turn_start` resets the denial circuit breaker, and `agent_settled` is the safe boundary for optional count-based analysis.
+The composition root registers the authorizer on the same `LocalPermissionsService` instance it publishes. `installBuiltinAutoReview()` returns lifecycle methods instead of registering a second set of Pi session handlers. The root's single `session_start` and `session_shutdown` handlers coordinate service publication and reviewer state, and `turn_start` resets the denial circuit breaker.
+
+The review model is configuration-only. `resolveReviewModel()` reads `autoReview.provider` / `autoReview.model` and looks the pair up in the live registry; it neither defaults the pair nor synthesizes a stand-in. An unconfigured, unknown-provider, or unpublished-model pair resolves to a failure category, which the reviewer records and turns into `defer`, so the ask reaches the human prompt instead of being decided by an unintended model.
 
 A separate `HardGuardPolicyLoader` supplies a global-only manager to `PermissionResolver`. Resolution is deliberately asymmetric:
 
@@ -511,8 +513,6 @@ ordinaryManager.check(intent, session rules)
 
 Thus hard-file `allow` means “not blocked by hard guards,” not “approved overall.” Ordinary policy, per-agent restrictions, session grants, yolo mode, and model authority cannot loosen a hard deny.
 
-Completed AutoReview verdicts flow to an owner-only count ledger. The reviewer callback strips rationale/transcript/raw payload and persists bounded fingerprints. Reaching the configured checkpoint marks analysis pending. At `agent_settled`, a tool-free, extension-free, in-memory AgentSession receives only aggregated records. Its strict JSON proposal is validated against the evidence, persisted, and injected into the same session as a follow-up. The checkpoint advances only after a valid proposal is stored; shutdown leaves pending work durable. No analysis path mutates either policy file.
-
 The public authorizer registry remains available for other named authorities. Configuration order determines chain order, unregistered names are skipped fail-safe, and registration alone grants no authority.
 
 Authorizers are named capabilities registered on `permissions:ready`; the integrated `auto-review` authorizer uses the same chain contract as third-party links. Once configured, a link's `allow` or `deny` is final for any ordinary-policy `ask`, including `path`; `defer` advances to the next link or terminal.
@@ -588,7 +588,7 @@ src/
 ├── authority/
 │   ├── authorizer-selection.ts  Configured authorizer resolution
 │   └── authorizer-chain.ts      Named authorizer ordering and terminal fallback
-├── auto-review/                 Integrated reviewer and count-based analysis
+├── auto-review/                 Integrated reviewer
 ├── service.ts                   Cross-extension permission service
 └── types.ts                     Shared domain types
 ```