fix(db): add missing apiKeys columns + restore ApiExplorerModal export

- schema.js: add createdAt/allowedModels to apiKeys, bump SCHEMA_VERSION 3->4
- shared/components/index.js: restore ApiExplorerModal barrel export (was replaced by TagInput)
- combos: tag support, repo + api + page updates

tmp/9r-smoke-dist/dev/server/server-reference-manifest.json

@@ -0,0 +1,5 @@
+{
+  "node": {},
+  "edge": {},
+  "encryptionKey": "+PzC19pP70GybS3k4K8t6RsdWKuh0Yqhwm2/p8Gxynw="
+}