Feat v0.5.3 chat polish + integration testing

Conversation search (db.query search_like, chat-core /search endpoint,
sidebar search UI), message pagination polish (scroll preservation,
loading spinner), workflow-chat integration package, and multi-user
E2E test infrastructure.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/sandbox/db_module_test.go

@@ -350,3 +350,83 @@ func TestDBListTables(t *testing.T) {
 	}
 }
 
+// ── search_like ─────────────────────────────
+
+func TestDBQuerySearchLike(t *testing.T) {
+	db, cfg := newTestDB(t)
+	db.Exec(`INSERT INTO ext_test_ext_logs (id, message, user_id) VALUES ('a', 'hello world', 'u1')`)
+	db.Exec(`INSERT INTO ext_test_ext_logs (id, message, user_id) VALUES ('b', 'goodbye world', 'u2')`)
+	db.Exec(`INSERT INTO ext_test_ext_logs (id, message, user_id) VALUES ('c', 'nothing here', 'u3')`)
+
+	result, err := execScript(t, cfg, `rows = db.query("logs", search_like={"message": "%hello%"})`)
+	if err != nil {
+		t.Fatalf("script error: %v", err)
+	}
+	rowsStr := result.Globals["rows"].String()
+	if !strings.Contains(rowsStr, "hello world") {
+		t.Errorf("expected hello world row, got: %s", rowsStr)
+	}
+	if strings.Contains(rowsStr, "goodbye") || strings.Contains(rowsStr, "nothing") {
+		t.Errorf("unexpected rows in search_like results: %s", rowsStr)
+	}
+}
+
+func TestDBQuerySearchLikeMultiColumn(t *testing.T) {
+	db, cfg := newTestDB(t)
+	db.Exec(`INSERT INTO ext_test_ext_logs (id, message, user_id) VALUES ('a', 'alpha', 'u1')`)
+	db.Exec(`INSERT INTO ext_test_ext_logs (id, message, user_id) VALUES ('b', 'beta', 'u-alpha')`)
+	db.Exec(`INSERT INTO ext_test_ext_logs (id, message, user_id) VALUES ('c', 'gamma', 'u3')`)
+
+	// Search across message OR user_id — should match both 'a' (message=alpha) and 'b' (user_id=u-alpha)
+	result, err := execScript(t, cfg, `rows = db.query("logs", search_like={"message": "%alpha%", "user_id": "%alpha%"})`)
+	if err != nil {
+		t.Fatalf("script error: %v", err)
+	}
+	rowsStr := result.Globals["rows"].String()
+	if !strings.Contains(rowsStr, "alpha") {
+		t.Errorf("expected alpha match, got: %s", rowsStr)
+	}
+	if strings.Contains(rowsStr, "gamma") {
+		t.Errorf("unexpected gamma row in multi-column search: %s", rowsStr)
+	}
+}
+
+func TestDBQuerySearchLikeWithFilters(t *testing.T) {
+	db, cfg := newTestDB(t)
+	db.Exec(`INSERT INTO ext_test_ext_logs (id, message, user_id) VALUES ('a', 'hello from u1', 'u1')`)
+	db.Exec(`INSERT INTO ext_test_ext_logs (id, message, user_id) VALUES ('b', 'hello from u2', 'u2')`)
+
+	// Combine search_like with filters — should only match u1's hello
+	result, err := execScript(t, cfg, `rows = db.query("logs", filters={"user_id": "u1"}, search_like={"message": "%hello%"})`)
+	if err != nil {
+		t.Fatalf("script error: %v", err)
+	}
+	rowsStr := result.Globals["rows"].String()
+	if !strings.Contains(rowsStr, "hello from u1") {
+		t.Errorf("expected u1 hello row, got: %s", rowsStr)
+	}
+	if strings.Contains(rowsStr, "hello from u2") {
+		t.Errorf("unexpected u2 row when filter + search_like combined: %s", rowsStr)
+	}
+}
+
+func TestDBQuerySearchLikeEmptyDict(t *testing.T) {
+	_, cfg := newTestDB(t)
+	// Empty search_like dict should be a no-op
+	_, err := execScript(t, cfg, `rows = db.query("logs", search_like={})`)
+	if err != nil {
+		t.Fatalf("empty search_like dict should not error: %v", err)
+	}
+}
+
+func TestDBQuerySearchLikeInvalidColumn(t *testing.T) {
+	_, cfg := newTestDB(t)
+	_, err := execScript(t, cfg, `rows = db.query("logs", search_like={"bad name": "%x%"})`)
+	if err == nil {
+		t.Fatal("expected error for invalid column name in search_like")
+	}
+	if !strings.Contains(err.Error(), "invalid column name") {
+		t.Errorf("unexpected error: %v", err)
+	}
+}
+