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/components/general/google-auth-button.tsx

@@ -4,16 +4,12 @@ import Row from "@moduletrace/twui/layout/Row";
 import Span from "@moduletrace/twui/layout/Span";
 import type useFormInit from "@/src/hooks/use-form-init";
 import { twMerge } from "tailwind-merge";
-import useGoogleAuth, {
-    type GoogleAuthMode,
-} from "@/src/hooks/use-google-auth";
+import useGoogleAuth from "@/src/hooks/use-google-auth";
 
 type Props = Pick<
     ReturnType<typeof useFormInit>,
     "loading" | "setLoading" | "setStatus"
-> & {
-    mode: GoogleAuthMode;
-};
+>;
 
 /**
  * Themed button with Google's own (transparent) button laid over it. Once
@@ -21,21 +17,18 @@ type Props = Pick<
  * themed button below is hidden from assistive tech.
  */
 export default function GoogleAuthButton({
-    mode,
     loading,
     setLoading,
     setStatus,
 }: Props) {
     const { handleButtonClick, googleButtonRef, googleReady } = useGoogleAuth({
-        mode,
         loading,
         setLoading,
         setStatus,
     });
 
     const overlayActive = googleReady && !loading;
-    const label =
-        mode == "signup" ? "Sign up with Google" : "Log in with Google";
+    const label = "Log in with Google";
 
     return (
         <Row className="w-full relative justify-center rounded-default focus-within:ring-2 focus-within:ring-primary/70">