feat(pi-hermes-memory): 接入持久记忆扩展并移除 Hippo

用仓库内 pi-hermes-memory 替换 hippo-memory-pi，清理 Hippo 在组合包中的
全部注入点。

移除 Hippo：
- 删除 hippo-memory-pi/ 与 config/hippo-memory-version。
- extensions/plugin-init.ts 只保留 CodeGraph 初始化目标与预检。
- install.sh / update.sh / uninstall.sh 移除 Hippo CLI 的安装、升级、卸载
  与版本校验逻辑；uninstall.sh 同时删除仅服务于该提示的死代码 ask_yes_no。
- 删除 tests/hippo-extension.test.ts 与 tests/hippo-scripts.test.ts。
- tests/extension-load.test.ts 反转“不得加载 Hermes”的断言为必须加载，
  并断言其排在 pi-compaction 之前。

接入 pi-hermes-memory：
- package.json 增加 file:./pi-hermes-memory 依赖、files 条目与加载入口；
  加载顺序位于 pi-compaction 之前，否则 flushOnCompact 会被 pi-compaction
  的 { cancel: true } 静默跳过。
- 六个记忆工具在 Tool Search 中常驻：memory_search 与 session_search 连同
  context_tree_query 归入 memory-recall，memory_add / memory_replace /
  memory_remove / skill_manage 归入 memory-management。常驻是必需的——注入
  的 memory policy 会在普通工作中指示模型调用它们，schema 不可见会让模型
  静默放弃而不是去 tool_search，同时常驻也保持请求前缀缓存稳定。
- bundleDefaultsVersion 由 2 升到 3；migrate-tool-search-settings.mjs 新增
  上一版快照到当前版本的迁移路径，仍只迁移完整匹配的默认快照并保留自定义
  配置。
- config/pi-permission-policy.jsonc 为六个工具设置 allow：它们只写扩展自己的
  agent 目录数据、不触碰工作区，且 memory_search 每轮都可能被调用，落入
  默认 ask 会产生每轮 AutoReview 往返。

依赖：
- pi-hermes-memory 的 devDependencies 由上游 ^0.80.2 等范围改为与根包一致的
  精确版本。上游范围与根包 0.84.2 不兼容，会让 npm 在本目录嵌套安装第二套
  Pi runtime（实测 229 MB），违反“不得在组合包内再安装一套 Pi runtime”的
  纪律。
- 根 allowScripts 保持只有 better-sqlite3@12.11.1。hermes 的
  better-sqlite3@13 运行时 dlopen 的是包内 N-API 预编译二进制
  prebuilds/<platform>.node，npm 因 binding.gyp 推断出的 node-gyp rebuild
  无需执行；实测删除 build/ 目录后仍正常工作。

文档：AGENTS.md 与 README.md 改写记忆章节，新增 pi-hermes-memory 开发约定，
替换文末的 Hippo 项目记忆块。

验证：根 12 个测试文件、pi-tool-search 的 typecheck/test/build、
pi-permission-system 的 typecheck/2569 测试、pi-hermes-memory 自带的 59 个
测试文件全部通过；隔离 Pi 环境联合加载无错误并生成 bundleDefaultsVersion 3；
npm install 幂等；迁移 helper 对 v2 快照迁移、对自定义配置保留。

tests/extension-load.test.ts

@@ -1,5 +1,5 @@
 import assert from "node:assert/strict";
-import { chmod, mkdir, mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
+import { mkdir, mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import { dirname, join, resolve } from "node:path";
 import { fileURLToPath } from "node:url";
@@ -29,14 +29,15 @@ test("all package extensions load together without global registration conflicts
 		dependencies: Record<string, string>;
 		files: string[];
 		pi: { extensions: string[] };
+		allowScripts: Record<string, boolean>;
 	};
 	assert.ok(
 		packageJson.pi.extensions.includes("./extensions/plugin-init.ts"),
 		"the bundle must expose the project plugin initializer command",
 	);
 	assert.ok(
-		packageJson.pi.extensions.includes("./hippo-memory-pi/index.ts"),
-		"the bundle must load the vendored official Hippo Memory extension",
+		packageJson.pi.extensions.includes("./pi-hermes-memory/src/index.ts"),
+		"the bundle must load the vendored Hermes memory extension",
 	);
 	assert.ok(
 		packageJson.pi.extensions.includes("./pi-minimal-footer/index.ts"),
@@ -145,19 +146,37 @@ test("all package extensions load together without global registration conflicts
 	assert.equal(packageJson.dependencies["@ogulcancelik/pi-minimal-footer"], "file:./pi-minimal-footer");
 	assert.equal(packageJson.dependencies["@tintinweb/pi-subagents"], undefined);
 	assert.equal(packageJson.pi.extensions.includes("./extensions/subagents.ts"), false);
+	assert.ok(
+		packageJson.pi.extensions.includes("./pi-hermes-memory/src/index.ts"),
+		"the bundle must load the locally maintained Hermes memory extension",
+	);
+	assert.equal(packageJson.dependencies["pi-hermes-memory"], "file:./pi-hermes-memory");
+	assert.ok(
+		packageJson.files.includes("pi-hermes-memory"),
+		"the packed bundle must include the locally maintained Hermes memory source",
+	);
+	assert.ok(
+		packageJson.pi.extensions.indexOf("./pi-hermes-memory/src/index.ts") <
+			packageJson.pi.extensions.indexOf("./pi-compaction/index.ts"),
+		"the memory extension must register its session_before_compact flush before the compaction authority can cancel the event",
+	);
 	assert.equal(
-		packageJson.pi.extensions.some((entry) => entry.includes("pi-hermes-memory") || entry.includes("the-forge-flow")),
+		packageJson.pi.extensions.some((entry) => entry.includes("hippo-memory-pi") || entry.includes("the-forge-flow")),
 		false,
-		"retired Hermes and third-party Hippo extensions must not be loaded",
+		"retired Hippo and third-party memory extensions must not be loaded",
 	);
 	assert.equal(packageJson.dependencies["@the-forge-flow/hippo-memory-pi"], undefined);
+	assert.equal(packageJson.dependencies["better-sqlite3"], undefined);
+	assert.equal(packageJson.allowScripts["better-sqlite3@12.11.1"], true);
+	assert.equal(
+		packageJson.allowScripts["better-sqlite3@13.0.3"],
+		undefined,
+		"Hermes uses better-sqlite3 13 N-API prebuilds, so no extra install-script approval is required",
+	);
 	assert.equal(packageJson.dependencies["@sinclair/typebox"], undefined);
 	const home = await mkdtemp(join(tmpdir(), "my-pi-extension-load-"));
 	const mockBin = join(home, "bin");
 	await mkdir(mockBin, { recursive: true });
-	const hippo = join(mockBin, "hippo");
-	await writeFile(hippo, "#!/bin/sh\nprintf '%s\\n' 'Hippo Memory status'\n", "utf8");
-	await chmod(hippo, 0o755);
 	const args = ["--no-extensions"];
 	for (const entry of packageJson.pi.extensions) args.push("-e", resolve(repositoryRoot, entry));
 	args.push("--mode", "rpc");