Infra: split dev and production (releases, services, deploy script)

- Production now runs from ~/freezmo-prod/current (release symlink) as a
  standalone server on :3207; releases are exported by scripts/deploy.sh,
  built and e2e-verified on a temp port, switched atomically, health-
  checked via the new /api/healthz (commit + build time) and rolled back
  automatically on failure. Last 5 releases kept; scripts/rollback.sh for
  manual rollback. Shared env + data live in ~/freezmo-prod/shared/ and
  are symlinked into every release (existing sync/push data migrated and
  verified identical).
- Dev runs from ~/freezmo via freezmo-dev.service: next dev on :3217
  (LAN only), its own build folder (.next-dev via NEXT_DIST_DIR), its own
  data (~/freezmo/.freezmo-dev), DEV badge, dev favicon/theme colour,
  "Freezmo Dev" PWA identity and never the production service worker.
- /api/healthz + the Settings Details version row (short commit + build
  time). output: standalone in next.config (next start still works).
- AGENTS.md documents the workflow rules: only dev updates during a task,
  temporary dirs/ports for test builds, and deploy-at-the-end as the only
  production path. README gains an Environments and deploy section.
- Fix found by the rehearsal: lib/dev-mode.ts must not be a client module
  (a server component importing a constant from a "use client" module
  gets a truthy proxy, which baked dev metadata into production builds).
- SW -> freezmo-v34.

components/AppHeader.tsx

@@ -6,6 +6,7 @@ import { useEffect, useState } from "react";
 import { SettingsDialog } from "@/components/SettingsDialog";
 import { TabBar } from "@/components/TabBar";
 import { ThemeToggle } from "@/components/ThemeToggle";
+import { IS_DEV_INSTANCE } from "@/lib/dev-mode";
 import { useI18n } from "@/lib/i18n";
 import { OPEN_SETTINGS_EVENT } from "@/lib/ui-events";
 import { cn } from "@/lib/utils";
@@ -61,6 +62,11 @@ export function AppHeader({ className, compact = false }: { className?: string;
             />
             <span className="flex min-w-0 items-baseline gap-2">
               <span className="text-[15px] font-semibold tracking-[-0.01em] text-[var(--text)]">Freezmo</span>
+              {IS_DEV_INSTANCE ? (
+                <span className="rounded-md border border-amber-400/60 bg-amber-400/15 px-1.5 py-0.5 text-[10px] font-bold uppercase tracking-wide text-amber-700 dark:text-amber-300">
+                  DEV
+                </span>
+              ) : null}
               {!compact ? (
                 <span className="hidden truncate text-[13px] text-[var(--text-subtle)] sm:inline">
                   {t("header.tagline")}

components/ServiceWorkerRegistrar.tsx

@@ -2,6 +2,8 @@
 
 import { useEffect } from "react";
 
+import { IS_DEV_INSTANCE } from "@/lib/dev-mode";
+
 /**
  * Registers the service worker in production builds only.
  *
@@ -11,6 +13,8 @@ import { useEffect } from "react";
 export function ServiceWorkerRegistrar() {
   useEffect(() => {
     if (process.env.NODE_ENV !== "production") return;
+    // A dev instance never registers the production worker, whatever the build.
+    if (IS_DEV_INSTANCE) return;
     if (typeof navigator === "undefined" || !("serviceWorker" in navigator)) return;
 
     const register = () => {

components/SettingsDialog.tsx

@@ -4,6 +4,7 @@ import { AnimatePresence, motion, useDragControls, useReducedMotion } from "fram
 import { useEffect, useRef, useState, useSyncExternalStore } from "react";
 
 import { LOCALES, useI18n, type Locale } from "@/lib/i18n";
+import { useVersion } from "@/lib/use-version";
 import { haptic } from "@/lib/haptics";
 import { modelErrorCopy } from "@/lib/model-errors";
 import { springSheet } from "@/lib/motion";
@@ -53,6 +54,7 @@ export function SettingsDialog({
   const { health, loading, error, refresh, apiKey, checkedAt } = useHealth();
   const installAvailable = useInstallAvailable();
   const { locale, setLocale, t, plural } = useI18n();
+  const version = useVersion();
   const keyInputRef = useRef<HTMLInputElement>(null);
   const settings = useSyncExternalStore(
     settingsStore.subscribe,
@@ -513,6 +515,17 @@ export function SettingsDialog({
                             mono
                             badge={modelBadge(health?.text)}
                           />
+                          {version ? (
+                            <DetailRow
+                              label={t("settings.version")}
+                              value={
+                                version.builtAt
+                                  ? `${version.short} · ${new Date(version.builtAt).toLocaleString()}`
+                                  : version.short
+                              }
+                              mono
+                            />
+                          ) : null}
                         </dl>
                         {health?.mode === "direct-cloud" && health.needsKey ? (
                           <p className="pt-2 text-[11px] leading-relaxed text-[var(--text-subtle)]">
@@ -782,6 +795,12 @@ export function SettingsDialog({
                 ) : null}
 
                 {health ? <HealthPanel health={health} /> : null}
+                {version ? (
+                  <p className="mt-2 text-[11px] text-[var(--text-subtle)]">
+                    {t("settings.version")}: <span className="font-mono">{version.short}</span>
+                    {version.builtAt ? ` · ${new Date(version.builtAt).toLocaleString()}` : ""}
+                  </p>
+                ) : null}
 
                 {/* keeps real content out of the 36px fade strip at the bottom */}
                 <div className="h-9" aria-hidden />

components/Sidebar.tsx

@@ -20,6 +20,7 @@ import {
 import { useTheme } from "@/components/ThemeToggle";
 import { createFolder, folderStore } from "@/lib/folders";
 import { haptic } from "@/lib/haptics";
+import { IS_DEV_INSTANCE } from "@/lib/dev-mode";
 import { useI18n } from "@/lib/i18n";
 import { ALL_FOLDERS, folderSelection, useSelectedFolder } from "@/lib/nav";
 import { UNORGANIZED_ID } from "@/lib/schemas";
@@ -102,7 +103,14 @@ function NavContent({ collapsed = false }: { collapsed?: boolean }) {
             className="size-7 shrink-0 rounded-lg shadow-[0_1px_3px_rgb(14_21_40/0.35)]"
           />
           {!collapsed ? (
-            <span className="text-[15px] font-semibold tracking-[-0.01em] text-[var(--text)]">Freezmo</span>
+            <>
+              <span className="text-[15px] font-semibold tracking-[-0.01em] text-[var(--text)]">Freezmo</span>
+              {IS_DEV_INSTANCE ? (
+                <span className="rounded-md border border-amber-400/60 bg-amber-400/15 px-1.5 py-0.5 text-[10px] font-bold uppercase tracking-wide text-amber-700 dark:text-amber-300">
+                  DEV
+                </span>
+              ) : null}
+            </>
           ) : null}
         </Link>
         {!collapsed ? (