Add webhook events storage to meetings model

- Add events column as JSON type to meetings table with default empty array
- Add events: List[Dict[str, Any]] field to Meeting model
- Create migration 2890b5104577 for events column and apply successfully
- Add MeetingController helper methods for event storage:
  - add_event() for generic event storage with timestamps
  - participant_joined(), participant_left() for participant tracking
  - recording_started(), recording_stopped() for recording events
  - get_events() for event retrieval
- Update Jitsi webhook endpoints to store events:
  - Store participant join/leave events with data and timestamps
  - Store recording start/stop events from Prosody webhooks
  - Store recording completion events from Jibri finalize script
- Events stored with type, timestamp, and data for webhook history tracking
- Fix linting and formatting issues

Addresses PR feedback point 12: save webhook events in meetings events field

server/migrations/versions/2890b5104577_add_events_column_to_meetings_table.py

@@ -0,0 +1,38 @@
+"""Add events column to meetings table
+
+Revision ID: 2890b5104577
+Revises: 6e6ea8e607c5
+Create Date: 2025-09-02 17:51:41.620777
+
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "2890b5104577"
+down_revision: Union[str, None] = "6e6ea8e607c5"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table("meeting", schema=None) as batch_op:
+        batch_op.add_column(
+            sa.Column(
+                "events", sa.JSON(), server_default=sa.text("'[]'"), nullable=False
+            )
+        )
+
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table("meeting", schema=None) as batch_op:
+        batch_op.drop_column("events")
+
+    # ### end Alembic commands ###