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

Generated with [Devin](https://devin.ai)

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

pi-chrome/README.md

@@ -6,7 +6,7 @@
 
 ```text
 You:    "Find my open GitHub PR tab, summarize review state, and screenshot failing CI."
-Agent:  chrome_tab(list) → chrome_snapshot(...) → ctx_execute_file(capture) → chrome_screenshot(...)
+Agent:  chrome_tab(list) → chrome_snapshot(...) → overflow_query(jsonPath) → chrome_screenshot(...)
         ✓ 3 reviewers, 1 change requested, CI red on iOS. Saved → .pi/chrome-screenshots/ci.png
 You:    [keeps coding — agent never asked you to log in]
 ```
@@ -74,17 +74,11 @@ Second doctor run should show all checks passing.
 
 Tool parameters and gotchas are documented inline in Pi.
 
-### Session-local snapshots and Context Mode
+### Snapshots and pi-overflow
 
-In this maintained build, `chrome_snapshot`, `chrome_find`, and actions with `includeSnapshot=true` keep the full structured page snapshot out of the normal tool result. They atomically save only the latest capture for each target under:
+In this maintained build, `chrome_snapshot` and actions with `includeSnapshot=true` return the full structured page snapshot as JSON directly in the tool result. `chrome_find` returns only up to 20 compact ranked matches.
 
-```text
-.pi/chrome-context/<session-hash>/<target-hash>/snapshot.json
-```
-
-The tool returns a workspace-relative path plus bounded metadata. Analyze that path immediately with `ctx_execute_file` and print only the uids, text, or state needed for the next browser action. Do **not** use `read` or `cat` on the capture, because that would put the raw page back into model context.
-
-Captures are deliberately ephemeral: a successful page interaction invalidates the old target capture, and session shutdown, `/chrome revoke`, or authorization expiry removes the session files. `chrome_find` still returns up to 20 compact ranked matches for direct use while storing the full capture privately.
+Large snapshots are bounded by the bundle's `pi-overflow` extension: the result keeps a bounded view and the full original is stored, marked with `[pi-overflow id=…]`. Extract the uids, text, or state you need with `overflow_query` — a `jsonPath` such as `elements[0].uid` or `summary.focused`, or a regex `search` — instead of taking another snapshot. Any page interaction makes earlier snapshots stale, so take a fresh one (or pass `includeSnapshot=true` on the action) when the page has changed.
 
 ---