feat(desktop): Contacts + Settings→Devices + expanded Profile + QR + keybinds (v2.2.0-rc1)

Completes the desktop feature surface ahead of the v2.2.0 tag. Only
auto-update + packaging remain.

Settings — now two-paned (nav on the left, pages on the right):
  * NodePage — URL ping-on-commit + API token field.
  * IdentityPage — pub key / X25519 pub, Export (safe-save dialog) /
    Import (open dialog + wipe + replace) / Delete identity.
  * DevicesPage — full multi-device UI: list every active device with
    a THIS DEVICE badge; Unlink button on every other row submits
    UNLINK_DEVICE + optimistic local remove; Link new device modal
    takes {code, device key, name}, submits LINK_DEVICE, then ships
    the handshake envelope (master Ed25519 priv encrypted for the
    new X25519) — same protocol as mobile's primary-device modal.
  * AboutPage — version, platform, Gitea links.
  * store.settingsPage discriminated union keeps selection across
    section switches.

Contacts section (now real):
  * ContactsList — alphabetical, filter-as-you-type; each row shows
    avatar letter + name + short address.
  * ContactsDetail — profile card (username/alias/pub) + Open chat /
    View posts / Copy address actions + stats grid
    (Balance, Devices, Encryption, Added) + Identity card with
    DC address, username, published X25519, device_count.
  * store.selectedContact persists across navigation.

Profile section (expanded):
  * ProfileList — big avatar + pub key + contacts count.
  * ProfileDetail — balance hero, quick actions (My posts →
    feed author wall, Manage devices → Settings→Devices, Copy
    address), Identity card, inline Linked devices list with a
    THIS DEVICE badge matching the Settings page.

Receive modal — canvas QR via `qrcode` (new dep, ~5 KB gzipped),
white-on-transparent so it sits inside the same black modal chrome.

Global keybinds (useGlobalKeybinds hook mounted in Shell):
  * Ctrl/Cmd+W — close the current conversation (drops activeChat,
    keeps section). Does NOT close the window.
  * Ctrl/Cmd+K — jump to Contacts.
  * Ctrl/Cmd+, — Settings.
  Each guards against being in a text field so typing `k,` in a
  composer / search doesn't hijack.

docs/ROADMAP.md — rc1 row flipped to done; v2.2.0 narrows to
auto-update + packaging + optional attachments in Compose.

desktop/src/sections/settings/SettingsNav.tsx

@@ -0,0 +1,61 @@
+// Left-pane category list for Settings. Keeps selection in
+// store.settingsPage so switching away and back preserves place.
+
+import React from 'react';
+import { useStore, type SettingsPage } from '@/lib/store';
+
+interface Row {
+  key:   SettingsPage;
+  label: string;
+  hint:  string;
+}
+
+const ROWS: Row[] = [
+  { key: 'node',     label: 'Node',     hint: 'URL, connection status'         },
+  { key: 'identity', label: 'Identity', hint: 'Your keys and address'          },
+  { key: 'devices',  label: 'Devices',  hint: 'Linked devices, pair a new one' },
+  { key: 'about',    label: 'About',    hint: 'Version, links'                 },
+];
+
+export function SettingsNav(): React.ReactElement {
+  const page    = useStore(s => s.settingsPage);
+  const setPage = useStore(s => s.setSettingsPage);
+  return (
+    <div style={{ padding: 10 }}>
+      {ROWS.map(r => (
+        <NavEntry
+          key={r.key}
+          label={r.label}
+          hint={r.hint}
+          active={page === r.key}
+          onClick={() => setPage(r.key)}
+        />
+      ))}
+    </div>
+  );
+}
+
+function NavEntry({
+  label, hint, active, onClick,
+}: { label: string; hint: string; active: boolean; onClick: () => void }) {
+  return (
+    <div
+      onClick={onClick}
+      style={{
+        padding: '10px 12px', borderRadius: 10, cursor: 'pointer',
+        background: active ? '#0a1a29' : 'transparent',
+        border: active ? '1px solid #1d9bf022' : '1px solid transparent',
+      }}
+      onMouseEnter={e => { if (!active) (e.currentTarget as HTMLDivElement).style.background = '#0a0a0a'; }}
+      onMouseLeave={e => { if (!active) (e.currentTarget as HTMLDivElement).style.background = 'transparent'; }}
+    >
+      <div style={{
+        color: active ? '#1d9bf0' : '#fff',
+        fontSize: 14, fontWeight: 700,
+      }}>{label}</div>
+      <div style={{ color: '#6a6a6a', fontSize: 11, marginTop: 2 }}>
+        {hint}
+      </div>
+    </div>
+  );
+}