Add skip tracking, compressed heatmap, listening log, docs, tests, and OpenAI support

Major changes:
- Add skip tracking: poll currently-playing every 15s, detect skips (<30s listened)
- Add listening-log and sessions API endpoints
- Fix ReccoBeats client to extract spotify_id from href response
- Compress heatmap from 24 hours to 6 x 4-hour blocks
- Add OpenAI support in narrative service (use max_completion_tokens for new models)
- Add ListeningLog component with timeline and list views
- Update all frontend components to use real data (album art, play counts)
- Add docker-compose external network (dockernet) support
- Add comprehensive documentation (API, DATA_MODEL, ARCHITECTURE, FRONTEND)
- Add unit tests for ingest and API endpoints

backend/alembic/versions/a1b2c3d4e5f6_add_skip_tracking_columns.py

@@ -0,0 +1,34 @@
+"""Add skip tracking columns to play_history
+
+Revision ID: a1b2c3d4e5f6
+Revises: f92d8a9264d3
+Create Date: 2025-12-29 22:30:00.000000
+
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = "a1b2c3d4e5f6"
+down_revision: Union[str, Sequence[str], None] = "f92d8a9264d3"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Add listened_ms, skipped, and source columns to play_history."""
+    op.add_column("play_history", sa.Column("listened_ms", sa.Integer(), nullable=True))
+    op.add_column("play_history", sa.Column("skipped", sa.Boolean(), nullable=True))
+    op.add_column("play_history", sa.Column("source", sa.String(), nullable=True))
+    # source can be: 'recently_played', 'currently_playing', 'inferred'
+
+
+def downgrade() -> None:
+    """Remove skip tracking columns."""
+    op.drop_column("play_history", "source")
+    op.drop_column("play_history", "skipped")
+    op.drop_column("play_history", "listened_ms")