Add rate limiting support to API keys

migrations/005_add_api_key_rate_limiting.sql

@@ -0,0 +1,6 @@
+-- Add rate limiting columns to api_keys table
+ALTER TABLE api_keys 
+ADD COLUMN IF NOT EXISTS rate_limit_count INTEGER,
+ADD COLUMN IF NOT EXISTS rate_limit_period VARCHAR(20), -- 'minute', 'hour', 'day'
+ADD COLUMN IF NOT EXISTS usage_count INTEGER DEFAULT 0,
+ADD COLUMN IF NOT EXISTS usage_reset_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP;