feat(events): reliable holiday skipping for recurrences + UI badge; clean logs

Backend: generate EventException on create/update when skip_holidays or recurrence changes; emit RecurrenceException (EXDATE) with exact occurrence start time (UTC)
API: return master events with RecurrenceRule + RecurrenceException
Frontend: map RecurrenceException → recurrenceException; ensure SkipHolidays instances never render on holidays; place TentTree icon (black) next to main event icon via template
Docs: update README and Copilot instructions for recurrence/holiday behavior
Cleanup: remove dataSource and debug console logs

server/alembic/versions/12ab34cd56ef_add_skip_holidays_to_events.py

@@ -0,0 +1,26 @@
+"""add skip_holidays to events
+
+Revision ID: 12ab34cd56ef
+Revises: 2b627d0885c3
+Create Date: 2025-10-12
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = '12ab34cd56ef'
+down_revision = '2b627d0885c3'
+branch_labels = None
+depends_on = None
+
+def upgrade():
+    op.add_column('events', sa.Column('skip_holidays', sa.Boolean(), nullable=False, server_default=sa.text('0')))
+    # Optional: create index if queries need it
+    # op.create_index('ix_events_skip_holidays', 'events', ['skip_holidays'])
+
+
+def downgrade():
+    # Optional: drop index
+    # op.drop_index('ix_events_skip_holidays', table_name='events')
+    op.drop_column('events', 'skip_holidays')