fix: add no-cache headers + remove debug console.logs

- Cache-Control/Pragma/Expires headers prevent browser caching
  of JS-heavy pages (fixes stale code after updates)
- Removed debug console.log statements from upload handlers

frontend/app.py

@@ -47,6 +47,10 @@ async def log_requests(request: Request, call_next):
     logger.info("→ %s %s (body %s bytes)", request.method, request.url.path, cl)
     try:
         response = await call_next(request)
+        # Prevent browser caching (especially important for JS-heavy pages)
+        response.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
+        response.headers["Pragma"] = "no-cache"
+        response.headers["Expires"] = "0"
         return response
     except Exception:
         logger.exception("← %s %s FAILED", request.method, request.url.path)

frontend/templates/index.html

@@ -71,7 +71,6 @@ function toggleSourceInput(e) {
 function setPhase(label, pct, isSpinner) {
   const el = document.getElementById('phase-label');
   const fill = document.getElementById('progress-fill');
-  console.log('[setPhase] el:', !!el, 'fill:', !!fill, 'label:', label, 'pct:', pct);
   if (el) el.innerHTML = (isSpinner ? '<span class="spinner"></span> ' : '') + label;
 }
 
@@ -135,8 +134,8 @@ async function handleUpload(formData) {
     xhr.timeout = 7200000;  // 2 hour timeout for very large uploads
 
     xhr.upload.addEventListener('progress', (e) => {
-      console.log('[upload] progress', e.loaded, e.total, e.lengthComputable);
       if (e.lengthComputable) {
+        const pct = Math.round((e.loaded / e.total) * 100);
         setPhase('Uploading source file... ' + (e.loaded / (1024**3)).toFixed(1) + ' GiB', pct, false);
       } else {
         // Fallback: show bytes uploaded even without total
@@ -145,7 +144,6 @@ async function handleUpload(formData) {
     });
 
     xhr.addEventListener('loadstart', () => {
-      console.log('[upload] loadstart');
       setPhase('Uploading source file...', 0, true);
     });