feat(sync): 长语音音频本地化(voice_clip media_hash+download+local-first playback)

Mirror download_call_recordings pattern for voice_clips:
- VoiceClip.media_hash column + Alembic migration (c4d5e6f7a8b9)
- VoiceClipOut.media_hash + frontend VoiceClip.media_hash type
- download_voice_clip_audio in app/scraper/media.py (resilient, sha256-dedup,
  same download_url/upsert_media helpers as call recordings)
- sync_voice_clip_audio orchestrator wrapper (commits own SyncRun, mirrors
  sync_call_recordings semantics)
- scheduler: _run_voice_clip_audio + ENTITY_FUNCS['voice_clip_audio'] +
  appended to daily _run_all job (after voice_clips)
- VoiceClipModal playClip local-first: /api/media/{media_hash} with OSS
  oss_file_name fallback (mirrors CallList.playRecord)

Tested: 376 pytest pass; vue-tsc clean; migration applied; 1523/1533 clips
localized (10 pending are genuine upstream HTTP 404s — resilient skip).

Co-Authored-By: Claude <noreply@anthropic.com>

yunke-server/migrations/versions/c4d5e6f7a8b9_voice_clip_media_hash.py

@@ -0,0 +1,34 @@
+"""voice_clip media_hash
+
+Revision ID: c4d5e6f7a8b9
+Revises: b3c4d5e6f7a8
+Create Date: 2026-08-11 00:00:00.000000
+
+"""
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'c4d5e6f7a8b9'
+down_revision: str | Sequence[str] | None = 'b3c4d5e6f7a8'
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # sha256 media_hash of the localized audio blob (FK -> Media.media_hash).
+    # NULL until sync_voice_clip_audio downloads it. batch_alter_table keeps
+    # this portable across SQLite (dev/test, table-recreate) and MySQL (prod,
+    # direct ALTER). Mirrors the phone_call.record_media_hash migration.
+    with op.batch_alter_table('voice_clip', schema=None) as batch_op:
+        batch_op.add_column(sa.Column('media_hash', sa.String(length=64), nullable=True))
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    with op.batch_alter_table('voice_clip', schema=None) as batch_op:
+        batch_op.drop_column('media_hash')