Add terminal client, memory, model fallback, version and install improvements

- codecraft: full-screen terminal client (ratatui) – local tools and files,
  models via the CodeCraft server gateway or own providers (standalone with a
  guided setup), slash commands, @files, permission dialogs, resume, update
- Static Linux CLI builds (x86_64/aarch64, cargo-zigbuild) served by the
  server: /cli/install.sh and /cli/download/<target>
- Project memory (remember tool, .codecraft/memory.md) and personal memory
- Model fallback when a host is unreachable or a budget is used up
- Version/commit in UI and health, daily release check, "What's new" dialog
- PWA: install button, maskable icon, manifest id and screenshots
- Case-insensitive detection of connection errors for retries

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/components/Sidebar.tsx

@@ -28,6 +28,7 @@ export function Sidebar({ open, activeId, section }: { open: boolean; activeId?:
   const permissions = useStore((s) => s.permissions);
   const questions = useStore((s) => s.questions);
   const me = useStore((s) => s.me);
+  const update = useStore((s) => s.update);
   // Full-text search over titles and messages.
   const [query, setQuery] = useState("");
   const [hits, setHits] = useState<{ id: string; title: string; cwd: string; agent: string; updated_at: number; snippet: string }[]>();
@@ -132,6 +133,11 @@ export function Sidebar({ open, activeId, section }: { open: boolean; activeId?:
           </div>
         ))}
       </nav>
+      {update && (
+        <a className="update-chip" href={update.url} target="_blank" rel="noreferrer" title={update.notes}>
+          <Icon name="sparkle" /> {t("update.available", { version: update.version })}
+        </a>
+      )}
       <div className="sidebar-user">
         <span title={me?.username}>
           {me?.display_name || me?.username}