Video compress: add output format selector (MP4/AVI/MKV)

- Compress panel now has format buttons before quality
- Backend uses selected format for compress output
- Format sent in API body for compress mode
- User can compress + convert format in one step

public/video.html

@@ -509,6 +509,16 @@
 
         <!-- Mode panel: Сжатие -->
         <div id="panel-compress" class="mode-panel" style="margin-bottom:24px;">
+            <div class="wa-card" style="margin-bottom:12px;">
+                <div class="option-group">
+                    <span class="option-label">Выходной формат</span>
+                    <div class="btn-group" id="compressFormats">
+                        <button class="btn-option selected" data-value="mp4">MP4</button>
+                        <button class="btn-option" data-value="avi">AVI</button>
+                        <button class="btn-option" data-value="mkv">MKV</button>
+                    </div>
+                </div>
+            </div>
             <div class="wa-card">
                 <div class="option-group">
                     <span class="option-label">Качество</span>
@@ -900,6 +910,7 @@
 
     initBtnGroup('convertFormats', val => { state.format = val; });
     initBtnGroup('audioFormats',   val => { state.audioFormat = val; });
+    initBtnGroup('compressFormats', val => { state.compressFormat = val; });
 
     // ─── Quality options ───────────────────────────────────────────────────────
     document.querySelectorAll('.quality-option').forEach(label => {
@@ -926,7 +937,8 @@
         const body = {
             jobId:     state.jobId,
             mode:      state.mode,
-            format:    state.mode === 'convert' ? state.format
+            format:    state.mode === 'compress' ? (state.compressFormat || 'mp4')
+                     : state.mode === 'convert' ? state.format
                      : state.mode === 'audio'   ? state.audioFormat
                      : state.mode === 'gif'     ? 'gif'
                      :                            'mp4',

routes/video.js

@@ -169,9 +169,10 @@ router.post('/convert', express.json(), async (req, res) => {
         break;
       }
       case 'compress': {
-        // Quality via mpeg4 q:v (1=best, 31=worst)
+        // Quality via mpeg4 q:v (1=best, 31=worst) + format selection
         const qv = quality === 'high' ? '3' : quality === 'low' ? '15' : '8';
-        args.push('-c:v', 'mpeg4', '-q:v', qv, '-c:a', 'aac', '-b:a', '128k', '-movflags', '+faststart');
+        args.push('-c:v', 'mpeg4', '-q:v', qv, '-c:a', 'aac', '-b:a', '128k');
+        if (format === 'mp4' || !format) args.push('-movflags', '+faststart');
         break;
       }
       case 'audio': {