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/package.json

@@ -1,6 +1,6 @@
 {
   "name": "dchain-desktop",
-  "version": "2.2.0-alpha6",
+  "version": "2.2.0-rc1",
   "description": "DChain desktop client — Electron shell mirroring the mobile app's functionality with a keyboard-first 3-panel layout.",
   "private": true,
   "main": "dist-electron/main.js",
@@ -13,6 +13,7 @@
     "typecheck": "tsc --noEmit -p tsconfig.json && tsc --noEmit -p electron/tsconfig.json"
   },
   "dependencies": {
+    "qrcode": "^1.5.4",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "tweetnacl": "^1.0.3",
@@ -20,6 +21,7 @@
     "zustand": "^5.0.3"
   },
   "devDependencies": {
+    "@types/qrcode": "^1.5.6",
     "@types/react": "^18.3.12",
     "@types/react-dom": "^18.3.1",
     "@vitejs/plugin-react": "^4.3.4",
@@ -38,8 +40,21 @@
       "dist/**/*",
       "dist-electron/**/*"
     ],
-    "mac":   { "target": ["dmg"] },
-    "win":   { "target": ["nsis"] },
-    "linux": { "target": ["AppImage", "deb"] }
+    "mac": {
+      "target": [
+        "dmg"
+      ]
+    },
+    "win": {
+      "target": [
+        "nsis"
+      ]
+    },
+    "linux": {
+      "target": [
+        "AppImage",
+        "deb"
+      ]
+    }
   }
 }