feat(pi-overflow): 新增统一的新工具结果展示截断扩展

此前截断分散在多层且互相冲突：Pi bash 保留尾部 50KB，RTK 兜底截断又只留
开头 12000 字符（砍掉报错与完整输出路径），pi-chrome 截开头 30K，web_fetch
各 provider 不一致。新扩展统一负责"新结果给模型看多少"：
- capture.ts 最先加载暂存原文，index.ts 最后加载（system-prompt 之前）
- 超过 24K 字符时原文落盘 <agentDir>/my-pi/pi-overflow/（700/600、原子写），
  优先取 bash fullOutputPath 完整文件；模型看到 头 + 中段信号行 + 尾 的有界
  视图，行号基于落盘原文、结尾永远可见
- overflow_query：按 id 正则搜索、行区间、jsonPath 只读查询，id 校验防穿越
- 收编：RTK truncate 默认关闭、删除 pi-chrome truncateText、web_fetch 默认
  每页 20000（上限 100000）、web_search max_results 限定 1–20
- pi-compaction 遮蔽带 details.overflow.id 的结果时在占位符提示 overflow_query
- 登记 tools.jsonc / routing / 权限 allow / tool-search 常驻与分组

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

pi-compaction/test/masking.test.ts

@@ -137,6 +137,27 @@ test("placeholder is deterministic, names the tool and call id, and truncates ar
   assert.ok(placeholder.includes("…"));
 });
 
+test("a masked result carrying details.overflow.id gets an overflow_query hint in the placeholder", () => {
+  const withOverflow = {
+    ...toolResultMessage("r1", "c1", "a".repeat(4_000)),
+    details: { overflow: { id: "0123456789ab", totalLines: 5, totalBytes: 4000, truncated: true } },
+  };
+  const withoutOverflow = toolResultMessage("r2", "c2", "b".repeat(4_000));
+  const entries = [
+    entry("e1", assistantMessage("a1", [{ id: "c1", name: "bash" }, { id: "c2", name: "bash" }])),
+    entry("e2", withOverflow),
+    entry("e3", withoutOverflow),
+    ...protect(),
+  ];
+  const masking = { ...MASKING, minClearTokens: 1 };
+  const plan = planMasking({ contextEntries: entries, currentTokens: 3_500, contextWindow: 0, masking, estimate });
+  assert.equal(plan.masked.length, 2);
+  const first = plan.masked.find((m) => m.toolCallId === "c1")!.placeholder;
+  const second = plan.masked.find((m) => m.toolCallId === "c2")!.placeholder;
+  assert.ok(first.includes(` Full original stored: overflow_query {"id":"0123456789ab"}.`));
+  assert.ok(!second.includes("overflow_query"));
+});
+
 test("the small-window ratio caps both trigger and target", () => {
   const masking: MaskingConfig = {
     ...MASKING,