WIP: Remove global state from pi-ai OAuth/API key handling

- Remove setApiKey, resolveApiKey, and global apiKeys Map from stream.ts
- Rename getApiKey to getApiKeyFromEnv (only checks env vars)
- Remove OAuth storage layer (storage.ts deleted)
- OAuth login/refresh functions now return credentials instead of saving
- getOAuthApiKey/refreshOAuthToken now take credentials as params
- Add test/oauth.ts helper for ai package tests
- Simplify root npm run check (single biome + tsgo pass)
- Remove redundant check scripts from most packages
- Add web-ui and coding-agent examples to biome/tsgo includes

coding-agent still has compile errors - needs refactoring for new API

biome.json

@@ -25,10 +25,11 @@
 	},
 	"files": {
 		"includes": [
-			"packages/*/src/**/*",
-			"packages/*/test/**/*",
-			"*.json",
-			"*.md",
+			"packages/*/src/**/*.ts",
+			"packages/*/test/**/*.ts",
+			"packages/coding-agent/examples/**/*.ts",
+			"packages/web-ui/src/**/*.ts",
+			"packages/web-ui/example/**/*.ts",
 			"!**/node_modules/**/*",
 			"!**/test-sessions.ts",
 			"!**/models.generated.ts",