feat: smart subtree-aware reinit and validate --fix

- project_map_reinit now regenerates only the target subtree + ancestors
  by default, falling back to full reinit when subtree file count exceeds
  reinitFullThresholdPercent (default 10%).
- Add reinitFullThresholdPercent config option.
- Expose fix=true on project_map_validate Pi tool for localized repair.
- Update docs and runtime guidance to prefer patch / validate --fix
  before full reinit.
- Add integration tests for smart reinit and update typebox mock.

tests/pi-extension.test.ts

@@ -16,6 +16,7 @@ vi.mock("typebox", () => ({
 		Object: (props: unknown) => props,
 		Optional: (prop: unknown) => prop,
 		String: (opts: unknown) => ({ type: "string", ...(opts as object) }),
+		Boolean: (opts: unknown) => ({ type: "boolean", ...(opts as object) }),
 	},
 }));
 
@@ -251,7 +252,7 @@ describe("pi-extension", () => {
 			await handler(null, mockCtx);
 
 			expect(mockNotify).toHaveBeenCalledWith(
-				expect.stringContaining("1 dirty packages detected"),
+				expect.stringContaining("1 dirty package(s) detected"),
 				"warning",
 			);
 		});