feat: Add comprehensive test suite and cleanup step

- Split validation into 4 granular CI steps (Config, Timescale, Vector, Hybrid)
- Added cleanup step for Docker images in CI
- Created SQL test scripts in tests/ for robustness

tests/test-1-config.sql

@@ -0,0 +1,17 @@
+-- Test 1: Configuration
+\set ON_ERROR_STOP on
+
+SELECT version();
+SELECT extname, extversion FROM pg_extension;
+
+DO $$
+DECLARE
+    preload_libs text;
+BEGIN
+    SELECT setting INTO preload_libs FROM pg_settings WHERE name = 'shared_preload_libraries';
+    IF preload_libs NOT LIKE '%timescaledb%' OR preload_libs NOT LIKE '%vchord%' THEN
+        RAISE EXCEPTION 'Missing shared_preload_libraries config. Found: %', preload_libs;
+    END IF;
+    RAISE NOTICE 'Configuration Check: OK';
+END
+$$;