fix(uninstall): remove gsd-file-manifest.json on uninstall (#1939)

The installer writes gsd-file-manifest.json to the runtime config root
at install time but uninstall() never removed it, leaving stale metadata
after every uninstall. Add fs.rmSync for MANIFEST_NAME at the end of the
uninstall cleanup sequence.

Regression test: tests/bug-1908-uninstall-manifest.test.cjs covers both
global and local uninstall paths.

Closes #1908

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

bin/install.js

@@ -4565,6 +4565,15 @@ function uninstall(isGlobal, runtime = 'claude') {
     }
   }
 
+  // Remove the file manifest that the installer wrote at install time.
+  // Without this step the metadata file persists after uninstall (#1908).
+  const manifestPath = path.join(targetDir, MANIFEST_NAME);
+  if (fs.existsSync(manifestPath)) {
+    fs.rmSync(manifestPath, { force: true });
+    removedCount++;
+    console.log(`  ${green}✓${reset} Removed ${MANIFEST_NAME}`);
+  }
+
   if (removedCount === 0) {
     console.log(`  ${yellow}⚠${reset} No GSD files found to remove.`);
   }