feat: persist isolated utility export jobs

controller/models.py

@@ -10,6 +10,7 @@ MEDIA_STATES = frozenset(
 )
 LIVE_JOB_STATES = frozenset({"reserved", "running"})
 LIVE_GUARD_STATES = frozenset({"active", "review_required"})
+UTILITY_EXPORT_MODES = frozenset({"mp4", "m4a", "mp3"})
 
 
 @dataclass(frozen=True)
@@ -54,6 +55,27 @@ class DownloadJob:
     error: str | None
 
 
+@dataclass(frozen=True)
+class ExportReservation:
+    status: str
+    job_id: str | None = None
+
+
+@dataclass(frozen=True)
+class ExportJob:
+    job_id: str
+    mode: str
+    url: str
+    status: str
+    submitter: str | None
+    note: str | None
+    requested_at: float
+    started_at: float | None
+    finished_at: float | None
+    output_paths: tuple[str, ...]
+    error: str | None
+
+
 @dataclass(frozen=True)
 class DeleteToken:
     slot: int