feat: add REST API server with download management

Very early dev work, more changes will be active in this branch.

- Implement download queue management and worker system
- Add OpenAPI/Swagger documentation
- Include download progress tracking and status endpoints
- Add API authentication and error handling
- Update core components to support API integration

unshackle/core/tracks/audio.py

@@ -12,6 +12,7 @@ class Audio(Track):
         AAC = "AAC"  # https://wikipedia.org/wiki/Advanced_Audio_Coding
         AC3 = "DD"  # https://wikipedia.org/wiki/Dolby_Digital
         EC3 = "DD+"  # https://wikipedia.org/wiki/Dolby_Digital_Plus
+        AC4 = "AC-4"  # https://wikipedia.org/wiki/Dolby_AC-4
         OPUS = "OPUS"  # https://wikipedia.org/wiki/Opus_(audio_format)
         OGG = "VORB"  # https://wikipedia.org/wiki/Vorbis
         DTS = "DTS"  # https://en.wikipedia.org/wiki/DTS_(company)#DTS_Digital_Surround
@@ -31,6 +32,8 @@ class Audio(Track):
                 return Audio.Codec.AC3
             if mime == "ec-3":
                 return Audio.Codec.EC3
+            if mime == "ac-4":
+                return Audio.Codec.AC4
             if mime == "opus":
                 return Audio.Codec.OPUS
             if mime == "dtsc":
@@ -60,6 +63,8 @@ class Audio(Track):
                 return Audio.Codec.AC3
             if profile.startswith("ddplus"):
                 return Audio.Codec.EC3
+            if profile.startswith("ac4"):
+                return Audio.Codec.AC4
             if profile.startswith("playready-oggvorbis"):
                 return Audio.Codec.OGG
             raise ValueError(f"The Content Profile '{profile}' is not a supported Audio Codec")

unshackle/core/tracks/tracks.py

@@ -202,17 +202,16 @@ class Tracks:
         """Sort audio tracks by bitrate, descriptive, and optionally language."""
         if not self.audio:
             return
-        # bitrate
-        self.audio.sort(key=lambda x: float(x.bitrate or 0.0), reverse=True)
         # descriptive
-        self.audio.sort(key=lambda x: str(x.language) if x.descriptive else "")
+        self.audio.sort(key=lambda x: x.descriptive)
+        # bitrate (within each descriptive group)
+        self.audio.sort(key=lambda x: float(x.bitrate or 0.0), reverse=True)
         # language
         for language in reversed(by_language or []):
             if str(language) in ("all", "best"):
                 language = next((x.language for x in self.audio if x.is_original_lang), "")
             if not language:
                 continue
-            self.audio.sort(key=lambda x: str(x.language))
             self.audio.sort(key=lambda x: not is_close_match(language, [x.language]))
 
     def sort_subtitles(self, by_language: Optional[Sequence[Union[str, Language]]] = None) -> None: