feat(monitoring): add server-side client logging and health infrastructure

- add Alembic migration c1d2e3f4g5h6 for client monitoring:
  - create client_logs table with FK to clients.uuid and performance indexes
  - extend clients with process/health tracking fields
- extend data model with ClientLog, LogLevel, ProcessStatus, and ScreenHealthStatus
- enhance listener MQTT handling:
  - subscribe to logs and health topics
  - persist client logs from infoscreen/{uuid}/logs/{level}
  - process health payloads and enrich heartbeat-derived client state
- add monitoring API blueprint server/routes/client_logs.py:
  - GET /api/client-logs/<uuid>/logs
  - GET /api/client-logs/summary
  - GET /api/client-logs/recent-errors
  - GET /api/client-logs/test
- register client_logs blueprint in server/wsgi.py
- align compose/dev runtime for listener live-code execution
- add client-side implementation docs:
  - CLIENT_MONITORING_SPECIFICATION.md
  - CLIENT_MONITORING_IMPLEMENTATION_GUIDE.md
- update TECH-CHANGELOG.md and copilot-instructions.md:
  - document monitoring changes
  - codify post-release technical-notes/no-version-bump convention

server/alembic/versions/c1d2e3f4g5h6_add_client_monitoring.py

@@ -0,0 +1,84 @@
+"""add client monitoring tables and columns
+
+Revision ID: c1d2e3f4g5h6
+Revises: 4f0b8a3e5c20
+Create Date: 2026-03-09 21:08:38.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = 'c1d2e3f4g5h6'
+down_revision = '4f0b8a3e5c20'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    bind = op.get_bind()
+    inspector = sa.inspect(bind)
+
+    # 1. Add health monitoring columns to clients table (safe on rerun)
+    existing_client_columns = {c['name'] for c in inspector.get_columns('clients')}
+    if 'current_event_id' not in existing_client_columns:
+        op.add_column('clients', sa.Column('current_event_id', sa.Integer(), nullable=True))
+    if 'current_process' not in existing_client_columns:
+        op.add_column('clients', sa.Column('current_process', sa.String(50), nullable=True))
+    if 'process_status' not in existing_client_columns:
+        op.add_column('clients', sa.Column('process_status', sa.Enum('running', 'crashed', 'starting', 'stopped', name='processstatus'), nullable=True))
+    if 'process_pid' not in existing_client_columns:
+        op.add_column('clients', sa.Column('process_pid', sa.Integer(), nullable=True))
+    if 'last_screenshot_analyzed' not in existing_client_columns:
+        op.add_column('clients', sa.Column('last_screenshot_analyzed', sa.TIMESTAMP(timezone=True), nullable=True))
+    if 'screen_health_status' not in existing_client_columns:
+        op.add_column('clients', sa.Column('screen_health_status', sa.Enum('OK', 'BLACK', 'FROZEN', 'UNKNOWN', name='screenhealthstatus'), nullable=True, server_default='UNKNOWN'))
+    if 'last_screenshot_hash' not in existing_client_columns:
+        op.add_column('clients', sa.Column('last_screenshot_hash', sa.String(32), nullable=True))
+
+    # 2. Create client_logs table (safe on rerun)
+    if not inspector.has_table('client_logs'):
+        op.create_table('client_logs',
+            sa.Column('id', sa.Integer(), autoincrement=True, nullable=False),
+            sa.Column('client_uuid', sa.String(36), nullable=False),
+            sa.Column('timestamp', sa.TIMESTAMP(timezone=True), nullable=False),
+            sa.Column('level', sa.Enum('ERROR', 'WARN', 'INFO', 'DEBUG', name='loglevel'), nullable=False),
+            sa.Column('message', sa.Text(), nullable=False),
+            sa.Column('context', sa.JSON(), nullable=True),
+            sa.Column('created_at', sa.TIMESTAMP(timezone=True), server_default=sa.func.current_timestamp(), nullable=False),
+            sa.PrimaryKeyConstraint('id'),
+            sa.ForeignKeyConstraint(['client_uuid'], ['clients.uuid'], ondelete='CASCADE'),
+            mysql_charset='utf8mb4',
+            mysql_collate='utf8mb4_unicode_ci',
+            mysql_engine='InnoDB'
+        )
+
+    # 3. Create indexes for efficient querying (safe on rerun)
+    client_log_indexes = {idx['name'] for idx in inspector.get_indexes('client_logs')} if inspector.has_table('client_logs') else set()
+    client_indexes = {idx['name'] for idx in inspector.get_indexes('clients')}
+
+    if 'ix_client_logs_client_timestamp' not in client_log_indexes:
+        op.create_index('ix_client_logs_client_timestamp', 'client_logs', ['client_uuid', 'timestamp'])
+    if 'ix_client_logs_level_timestamp' not in client_log_indexes:
+        op.create_index('ix_client_logs_level_timestamp', 'client_logs', ['level', 'timestamp'])
+    if 'ix_clients_process_status' not in client_indexes:
+        op.create_index('ix_clients_process_status', 'clients', ['process_status'])
+
+
+def downgrade():
+    # Drop indexes
+    op.drop_index('ix_clients_process_status', table_name='clients')
+    op.drop_index('ix_client_logs_level_timestamp', table_name='client_logs')
+    op.drop_index('ix_client_logs_client_timestamp', table_name='client_logs')
+    
+    # Drop table
+    op.drop_table('client_logs')
+    
+    # Drop columns from clients
+    op.drop_column('clients', 'last_screenshot_hash')
+    op.drop_column('clients', 'screen_health_status')
+    op.drop_column('clients', 'last_screenshot_analyzed')
+    op.drop_column('clients', 'process_pid')
+    op.drop_column('clients', 'process_status')
+    op.drop_column('clients', 'current_process')
+    op.drop_column('clients', 'current_event_id')