Add services layer, tests, streaming UI, and cleanup legacy code

crawler/alembic/versions/a1b2c3d4e5f6_add_streaming_indexes.py

@@ -0,0 +1,56 @@
+"""add streaming indexes for query optimization
+
+Revision ID: a1b2c3d4e5f6
+Revises: e5f1bc4e3323
+Create Date: 2026-02-01 12:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'a1b2c3d4e5f6'
+down_revision: Union[str, None] = 'e5f1bc4e3323'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Add composite and single-column indexes for streaming query optimization."""
+    # Composite index for main query pattern (bedrooms, price, last_seen filtering)
+    op.create_index(
+        'ix_rentlisting_query_composite',
+        'rentlisting',
+        ['number_of_bedrooms', 'price', 'last_seen'],
+        unique=False
+    )
+    op.create_index(
+        'ix_buylisting_query_composite',
+        'buylisting',
+        ['number_of_bedrooms', 'price', 'last_seen'],
+        unique=False
+    )
+
+    # Missing single-column indexes for frequently filtered columns
+    op.create_index(
+        'ix_rentlisting_furnish_type',
+        'rentlisting',
+        ['furnish_type'],
+        unique=False
+    )
+    op.create_index(
+        'ix_rentlisting_available_from',
+        'rentlisting',
+        ['available_from'],
+        unique=False
+    )
+
+
+def downgrade() -> None:
+    """Remove streaming indexes."""
+    op.drop_index('ix_rentlisting_available_from', table_name='rentlisting')
+    op.drop_index('ix_rentlisting_furnish_type', table_name='rentlisting')
+    op.drop_index('ix_buylisting_query_composite', table_name='buylisting')
+    op.drop_index('ix_rentlisting_query_composite', table_name='rentlisting')