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/layouts/bots/(partials)/rail-crew-list.tsx

@@ -0,0 +1,35 @@
+import type { BotWithLastMessage } from "@/src/types";
+import CoordinatorRow from "./coordinator-row";
+import BotRow from "./bot-row";
+
+type Props = {
+    bots: BotWithLastMessage[];
+    selected_id?: number;
+};
+
+/**
+ * The pinned coordinator, then the crew.
+ */
+export default function RailCrewList({ bots, selected_id }: Props) {
+    const coordinator = bots.find((bot) => bot.kind === "coordinator");
+    const workers = bots.filter((bot) => bot.kind !== "coordinator");
+
+    return (
+        <>
+            {coordinator ? (
+                <CoordinatorRow
+                    bot={coordinator}
+                    bots={bots}
+                    selected={coordinator.id === selected_id}
+                />
+            ) : null}
+            {workers.map((bot) => (
+                <BotRow
+                    key={bot.id}
+                    bot={bot}
+                    selected={bot.id === selected_id}
+                />
+            ))}
+        </>
+    );
+}