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-3-vector.sql

@@ -0,0 +1,27 @@
+-- Test 3: VectorChord / pgvector
+\set ON_ERROR_STOP on
+
+DROP TABLE IF EXISTS items;
+
+CREATE TABLE items (
+    id bigserial PRIMARY KEY, 
+    embedding vector(3)
+);
+
+INSERT INTO items (embedding) VALUES ('[1,2,3]'), ('[4,5,6]'), ('[1.1, 2.1, 3.1]');
+
+-- Create VectorChord Index
+CREATE INDEX ON items USING vchordrq (embedding vector_l2_ops);
+
+-- Search
+DO $$
+DECLARE
+    closest_id int;
+BEGIN
+    SELECT id INTO closest_id FROM items ORDER BY embedding <-> '[1,2,3]' LIMIT 1;
+    IF closest_id != 1 THEN
+        RAISE EXCEPTION 'Vector search failed. Expected ID 1, got %', closest_id;
+    END IF;
+    RAISE NOTICE 'Vector Check: OK';
+END
+$$;