fix(videos): real ffmpeg progress via -progress pipe, exclude .converting.mp4

- ffmpeg -progress pipe:1 streams out_time_ms lines; we parse them in the
  reading loop so % = out_time_s / duration_s (actual encode position)
- find_video_files() skips *.converting.mp4 temp files so they are never
  listed, uploaded, or shown in the UI

Co-authored-by: Copilot <[email protected]>

modules/app_video.py

@@ -71,19 +71,33 @@ def _convert_bg(relative_path):
                 if relative_path in _converting:
                     _converting[relative_path]["duration_s"] = duration_s
                     _converting[relative_path]["tmp_path"] = tmp_path
+                    _converting[relative_path]["out_time_s"] = 0.0
             cmd = [
                 "ffmpeg", "-nostdin", "-loglevel", "error", "-y",
                 "-i", source_path,
                 "-c:v", "h264_v4l2m2m",
-                "-b:v", "4M",        # 4 Mbps — good quality, ~100MB per 3-min clip
+                "-b:v", "4M",
                 "-c:a", "aac",
                 "-b:a", "128k",
                 "-movflags", "faststart",
                 "-f", "mp4",
+                "-progress", "pipe:1",
                 tmp_path,
             ]
-            proc = subprocess.Popen(cmd, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
-            proc.wait()  # real thread — blocking wait is fine
+            proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL,
+                                    text=True, bufsize=1)
+            # Read progress lines from stdout
+            for line in proc.stdout:
+                line = line.strip()
+                if line.startswith("out_time_ms="):
+                    try:
+                        ms = int(line.split("=", 1)[1])
+                        with _converting_lock:
+                            if relative_path in _converting:
+                                _converting[relative_path]["out_time_s"] = ms / 1_000_000.0
+                    except (ValueError, IndexError):
+                        pass
+            proc.wait()
             if proc.returncode == 0 and os.path.isfile(tmp_path) and os.path.getsize(tmp_path) > 0:
                 os.replace(tmp_path, mp4_path)
                 # Delete original now that MP4 is ready
@@ -152,7 +166,8 @@ def list_local_videos():
         if converting and conv_info:
             elapsed = time.time() - conv_info["started_at"]
             duration_s = conv_info.get("duration_s", 0)
-            pct = min(round(elapsed / duration_s * 100), 99) if duration_s > 0 else 0
+            out_time_s = conv_info.get("out_time_s", 0.0)
+            pct = min(round(out_time_s / duration_s * 100), 99) if duration_s > 0 else 0
             convert_progress = {
                 "elapsed_s": int(elapsed),
                 "pct": pct,