feat(v0.3): keybar Claude shortcuts + scrollback search + clickable links

- keybar: add Esc·Esc / ^O / ^T / ^B + per-button tooltips (KEY_MAP 14 keys)
- M1 search: @xterm/addon-search per terminal; 🔍 toolbar button + search box
  (Enter=next, Shift+Enter=prev, Esc=close)
- M2 links: @xterm/addon-web-links per terminal (tap URLs Claude prints)
- tab bar split into #tabs (scrollable) + #toolbar (utility cluster) for future
  utilities (QR/settings/dashboard)
- Browser-verified: 14 keybar buttons, search highlights matches, no console errors.
  199 tests green, typechecks + build ok.

package.json

@@ -20,14 +20,18 @@
   },
   "dependencies": {
     "@xterm/addon-fit": "^0.11.0",
+    "@xterm/addon-search": "^0.16.0",
+    "@xterm/addon-web-links": "^0.12.0",
     "@xterm/xterm": "^6.0.0",
     "express": "^5.2.1",
     "node-pty": "^1.1.0",
+    "qrcode": "^1.5.4",
     "ws": "^8.21.0"
   },
   "devDependencies": {
     "@types/express": "^5.0.6",
     "@types/node": "^25.9.3",
+    "@types/qrcode": "^1.5.6",
     "@types/ws": "^8.18.1",
     "esbuild": "^0.28.1",
     "tsx": "^4.22.4",