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/prerender-manifest.json

@@ -0,0 +1,11 @@
+{
+  "version": 4,
+  "routes": {},
+  "dynamicRoutes": {},
+  "notFoundRoutes": [],
+  "preview": {
+    "previewModeId": "ccf2fc358f0d676072b2c8a97c13bb23",
+    "previewModeSigningKey": "2d92942cd8170b1f834dbada55904274205957eacff5167dcde5bb52c19403ec",
+    "previewModeEncryptionKey": "a139b9d52f12448b1c4fe91cb68fc842bda57b8c35acb25a5a052a0e16e145fa"
+  }
+}