feat(prompt): 搜索引导改为意图→工具的正向指引，multi_grep 按上游保持关闭

真实会话中模型仍用 bash grep -o | sort -u 做抽取，被拒后直接放弃核对；
原提示词只说"不要"，没告诉它抽取/计数、给程序传文件清单、过滤命令输出时该用什么。

- routing：按已知信息选 grep/find（多变体用 grep 正则 alternation），
  codemode + tools.grep 做聚合，bash 文件清单用 git ls-files，
  overflow_query 过滤输出，被拒后改用替代方案继续
- 权限策略：rg/grep/git grep/find/fd 的 deny 附带指向替代工具的 reason
- tools.jsonc：grep/find 新 snippet，补上 codegraph_explore snippet
- FFF 上游标注 multi_grep 有害：wrapper 删除 PI_FFF_MULTIGREP，清理全部引用
- JSONC 测试改用字符串感知的注释剥离（reason 中含 'src/**/*.ts'）

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

tests/extension-load.test.ts

@@ -343,4 +343,12 @@ test("all package extensions load together without global registration conflicts
 	const codemode = probe.all.find((tool) => tool.name === "codemode");
 	assert.equal(codemode?.exposure, "model-only", "Pi's built-in codemode must load with model-only exposure");
 	assert.ok(probe.active.includes("codemode"), "Tool Search must pin codemode into the active set");
+	assert.ok(
+		probe.all.every((tool) => tool.name !== "multi_grep"),
+		"FFF's upstream-flagged multi_grep must stay unregistered (fff-override deletes PI_FFF_MULTIGREP)",
+	);
+	assert.ok(
+		!probe.active.includes("multi_grep"),
+		"multi_grep must not appear in the active tool set",
+	);
 });