chore: remove dead code and unused dependencies

Cleans up stale implementation artifacts:
- Delete legacy `src/webhook.ts` (dead code per AGENTS.md)
- Delete admin composables `useMe.ts` and `useRoutes.ts`
- Remove unused dependencies `jose` and `yaml`
- Remove stale `Me` interface, `FILTER_LABELS`, `invalidateConfigCache`, and formatter re-exports

src/config.ts

@@ -33,10 +33,6 @@ export async function saveRoutes(kv: KVNamespace, routes: Route[]): Promise<void
   configCache = null;
 }
 
-export function invalidateConfigCache(): void {
-  configCache = null;
-}
-
 export async function loadConfig(env: Env): Promise<Config> {
   if (configCache && Date.now() < configCache.expiresAt) {
     return configCache.config;