feat: add runtime policy and observability

migrations/009_runtime_policy_defaults.sql

@@ -0,0 +1,18 @@
+UPDATE system_config
+SET value = '{
+  "anonymous_per_minute": 10,
+  "anonymous_units_per_day": 10,
+  "user_per_minute": 60,
+  "api_key_per_minute": 100,
+  "login_ip_per_5_minutes": 30,
+  "login_identity_per_5_minutes": 10,
+  "register_ip_per_hour": 10,
+  "verification_email_per_minute": 1,
+  "email_verify_ip_per_15_minutes": 20,
+  "forgot_password_ip_per_15_minutes": 5,
+  "forgot_password_email_per_15_minutes": 3,
+  "password_reset_ip_per_15_minutes": 10,
+  "password_reset_token_per_15_minutes": 5
+}'::jsonb || value,
+    updated_at = NOW()
+WHERE key = 'rate_limits';