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.

src/cli/cli.ts

@@ -28,7 +28,7 @@ function printUsage() {
 		`  project-map ${pc.cyan("validate")} [--fix] [path]  Check for stale/missing/orphaned entries`,
 	);
 	console.log(
-		`  project-map ${pc.cyan("reinit")} [path]           Force full regeneration`,
+		`  project-map ${pc.cyan("reinit")} [path]           Regenerate a subtree or the whole project`,
 	);
 	console.log(
 		`  project-map ${pc.cyan("--help")}                 Show this help message`,
@@ -252,7 +252,7 @@ async function main() {
 			await reinitPath(targetPath, {
 				verbose: false,
 				llmClient: client,
-				cacheDir: targetPath,
+				cacheDir: process.cwd(),
 				onProgress: (info) => {
 					const line = renderProgressBar(
 						info.completed,