refactor: 移除 context-mode，Chrome 快照改为直接返回

context-mode 的 ctx_execute 系工具以真实 shell 执行且权限为 allow，绕过了
bash 策略与 protectedWrites；其每轮注入、独立 MCP 子进程与 skills 也与组合包
提示词单一所有权冲突。大输出职责已由 pi-overflow（入口截断）与
pi-compaction（压力遮蔽）承担：
- 删除 context-mode 依赖、wrapper/过滤器、skills，以及 ctx_* 的权限、
  tools.jsonc、路由规则、tool-search 常驻与 4 个分组
- better-sqlite3@12 仅为 context-mode 传递依赖，随之移除根 allowScripts
- pi-chrome：按用户决定移除快照隐私规则与 .pi/chrome-context 临时文件机制，
  快照 JSON 直接作为工具结果返回、details 只留小型元数据，超长由 pi-overflow
  截断并用 overflow_query 提取；授权生命周期不变

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

tests/web-search.test.ts

@@ -5,7 +5,7 @@ import test from "node:test";
 const packageJson = JSON.parse(await readFile(new URL("../package.json", import.meta.url), "utf8")) as {
 	dependencies: Record<string, string>;
 	files: string[];
-	pi: { extensions: string[]; skills: string[] };
+	pi: { extensions: string[]; skills?: string[] };
 };
 
 const filesIncludePackageDir = (files: string[], packageDir: string): boolean =>
@@ -45,7 +45,7 @@ test("no extension in the bundle loads the MCP adapter or upstream search extens
 });
 
 test("the keenable skill path is gone with the upstream package", () => {
-	for (const skillPath of packageJson.pi.skills) {
+	for (const skillPath of packageJson.pi.skills ?? []) {
 		assert.equal(skillPath.includes("@keenable"), false);
 	}
 });