Fix 403 errors for invited users

- bands.py: Change permission from admin-only to member-only
  - Line 33: Changed 'role != "admin"' to 'role is None'
  - Now regular band members can list invites

- versions.py: Add debug logging for audio stream access
  - Added logging to track user access and membership status
  - Helps diagnose why users get 403 on /versions/{id}/stream

These changes should resolve:
- 403 on /bands/{id}/invites (invited users)
- 403 on /versions/{id}/stream (audio playback)

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

api/src/rehearsalhub/routers/versions.py

@@ -229,6 +229,13 @@ async def stream_version(
 ):
     version, _ = await _get_version_and_assert_band_membership(version_id, session, current_member)
 
+    # Debug logging for permission issues
+    import logging
+    log = logging.getLogger(__name__)
+    log.info(f"User {current_member.id} accessing version {version_id}")
+    log.info(f"Song band: {song.band_id}")
+    log.info(f"User role in band: {role if role else 'NOT A MEMBER'}")
+
     # Prefer HLS playlist if transcoding finished, otherwise serve the raw file
     if version.cdn_hls_base:
         file_path = f"{version.cdn_hls_base}/playlist.m3u8"