Make Cobble a local install: setup flow, bots-first admin, settings

Local, password-only auth:
- No public pages; everything outside /admin and /auth redirects in
- First run (no users) sends every page to /auth/signup, which creates
  the super admin (user #1) once and then locks
- Login is email/username + password; removed the emailed-code flow,
  /auth/sso and email password reset
- Google login kept for existing accounts only, never creates them
- seed-super-admin now requires SEED_SUPER_ADMIN_PASSWORD

Bots-first admin:
- /admin and closed sections (people, logs, backups) redirect to
  /admin/bots; only bots and settings are live (AdminSections)
- Removed the old admin layout; every /admin page uses the bots rail
- Coordinator bot created at signup/seed and by /admin/bots
  (ensureCoordinatorBot), which redirects to its chat
- bots.system_prompt (markdown) with a default coordinator prompt
- seed-bots reuses the existing coordinator

Settings:
- Sub pages general (default), profile, change-password, listed in the
  rail with a back link; unknown settings paths redirect to general
- Redesigned settings UI: pane header, grouped rows, sticky save bar
- General: System/Light/Dark theme, saved per device

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/pages/admin/settings/(functions)/grab-settings-server-props.ts

@@ -1,4 +1,5 @@
 import userAuth from "@/src/functions/backend/auth/user-auth";
+import { AdminHomePath } from "@/src/dict/admin-sections-dict";
 import grabUsers from "@/src/functions/backend/db/users/grab-users";
 import sanitizeUserBio from "@/src/functions/backend/db/users/sanitize-user-bio";
 import grabUserPasswordHash from "@/src/functions/backend/auth/grab-user-password-hash";
@@ -26,7 +27,7 @@ export default async function grabSettingsServerProps({ req }: Params) {
     if (!user_res.singleRes) {
         return {
             redirect: {
-                destination: "/admin",
+                destination: AdminHomePath,
             },
         };
     }