fix(backup): create backups only when settings content changes

Previously, PUT /api/settings/:profile created a backup on every request
regardless of whether the content actually changed. This led to hundreds
of identical backup files accumulating in ~/.ccs/backups/.

Changes:
- Compare existing content with new content before creating backup
- Reuse computed newContent for atomic write (DRY)
- Make hook injection idempotent by checking content before write

Fixes #433

src/utils/websearch/profile-hook-injector.ts

@@ -123,13 +123,19 @@ export function ensureProfileHooks(profileName: string): boolean {
       // Clean up any duplicates that may have accumulated (Windows path bug fix)
       const hadDuplicates = deduplicateCcsHooks(settings);
       if (hadDuplicates) {
-        fs.writeFileSync(settingsPath, JSON.stringify(settings, null, 2), 'utf8');
+        // Re-read file to compare with modified settings (deduplicateCcsHooks mutates in-place)
+        const newContent = JSON.stringify(settings, null, 2);
+        const existingContent = fs.readFileSync(settingsPath, 'utf8');
+        // Only write if content actually changed
+        if (newContent !== existingContent) {
+          fs.writeFileSync(settingsPath, newContent, 'utf8');
           if (process.env.CCS_DEBUG) {
             console.error(
               info(`Removed duplicate WebSearch hooks from ${profileName}.settings.json`)
             );
           }
         }
+      }
       // Update timeout if needed
       return updateHookTimeoutIfNeeded(settings, settingsPath);
     }

src/web-server/routes/settings-routes.ts

@@ -156,9 +156,13 @@ router.put('/:profile', (req: Request, res: Response): void => {
       }
     }
 
-    // Create backup only if file exists
+    // Create backup only if file exists AND content actually changed
     let backupPath: string | undefined;
+    const newContent = JSON.stringify(settings, null, 2) + '\n';
     if (fileExists) {
+      const existingContent = fs.readFileSync(settingsPath, 'utf8');
+      // Only create backup if content differs
+      if (existingContent !== newContent) {
         const backupDir = path.join(ccsDir, 'backups');
         if (!fs.existsSync(backupDir)) {
           fs.mkdirSync(backupDir, { recursive: true });
@@ -167,6 +171,7 @@ router.put('/:profile', (req: Request, res: Response): void => {
         backupPath = path.join(backupDir, `${profile}.${timestamp}.settings.json`);
         fs.copyFileSync(settingsPath, backupPath);
       }
+    }
 
     // Ensure directory exists for new files
     if (!fileExists) {
@@ -175,7 +180,7 @@ router.put('/:profile', (req: Request, res: Response): void => {
 
     // Write new settings atomically
     const tempPath = settingsPath + '.tmp';
-    fs.writeFileSync(tempPath, JSON.stringify(settings, null, 2) + '\n');
+    fs.writeFileSync(tempPath, newContent);
     fs.renameSync(tempPath, settingsPath);
 
     const newStat = fs.statSync(settingsPath);