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

admin/composables/useMe.ts

@@ -1,30 +0,0 @@
-import type { Me } from "~/types";
-
-export function useMeApi() {
-  const me = ref<Me | null>(null);
-  const loading = ref(false);
-  const needLogin = ref(false);
-
-  async function load(): Promise<void> {
-    loading.value = true;
-    needLogin.value = false;
-    try {
-      const res = await fetch("/admin/api/me", {
-        headers: { accept: "application/json" },
-        credentials: "same-origin",
-      });
-      if (res.status === 401) {
-        needLogin.value = true;
-        return;
-      }
-      if (!res.ok) throw new Error(`HTTP ${res.status}`);
-      me.value = (await res.json()) as Me;
-    } catch {
-      me.value = null;
-    } finally {
-      loading.value = false;
-    }
-  }
-
-  return { me, loading, needLogin, load };
-}

admin/composables/useRoutes.ts

@@ -1,51 +0,0 @@
-import type { Route } from "~/types";
-
-export function useRoutesApi() {
-  const routes = ref<Route[]>([]);
-  const loading = ref(false);
-  const needLogin = ref(false);
-  const error = ref("");
-
-  async function load(): Promise<void> {
-    loading.value = true;
-    error.value = "";
-    needLogin.value = false;
-    try {
-      const res = await fetch("/admin/api/routes", {
-        headers: { accept: "application/json" },
-        credentials: "same-origin",
-      });
-      if (res.status === 401) {
-        needLogin.value = true;
-        return;
-      }
-      if (!res.ok) throw new Error(`HTTP ${res.status}`);
-      const data = (await res.json()) as { routes?: Route[] };
-      routes.value = data.routes ?? [];
-    } catch (err) {
-      error.value = err instanceof Error ? err.message : String(err);
-    } finally {
-      loading.value = false;
-    }
-  }
-
-  async function save(next: Route[]): Promise<void> {
-    const res = await fetch("/admin/api/routes", {
-      method: "PUT",
-      headers: { "content-type": "application/json" },
-      credentials: "same-origin",
-      body: JSON.stringify({ routes: next }),
-    });
-    if (res.status === 401) {
-      needLogin.value = true;
-      throw new Error("unauthorized");
-    }
-    if (!res.ok) {
-      const data = (await res.json().catch(() => ({}))) as { error?: string };
-      throw new Error(data.error ?? `HTTP ${res.status}`);
-    }
-    routes.value = next;
-  }
-
-  return { routes, loading, needLogin, error, load, save };
-}