feat(clients/decky): SteamOS Gaming-Mode launcher plugin (spike)

A Decky Loader plugin so a Steam Deck / SteamOS box can launch the punktfunk
client from Gaming Mode using REAL Steam UI components (it runs inside Steam's
CEF, so the panel is built from @decky/ui — the literal Big Picture primitives,
not a replica).

- Frontend (src/index.tsx, @decky/api + @decky/ui): a Quick Access Menu panel —
  Refresh → discover hosts, a native list (name, ip:port, pairing flag), tap to
  connect with a status toast, Disconnect.
- Backend (main.py): discover() shells `avahi-browse -rpt _punktfunk._udp` and
  parses the host's advertised TXT keys (proto/fp/pair/id from discovery.rs),
  dedup by id preferring IPv4; connect() resolves + spawns
  `punktfunk-client --connect host:port` (gamescope composites its video like a
  game), tracking the child; disconnect() terminates it.
- Mirrors the current official Decky template (the API moved to @decky/ui +
  @decky/api). Frontend builds clean (pnpm build → dist/index.js); main.py
  py_compiles. dist/ + node_modules gitignored — build on the Deck per README.

Spike scope: launcher only, runtime untested (no Deck here). Next on this track:
the in-stream Quick-Access overlay (volume/disconnect/stats over the running
stream) and a fuller real-components UI. Client decode on the AMD Deck is the
existing VAAPI path; the host-encode VAAPI gap is separate (NVIDIA host = NVENC).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/decky/package.json

@@ -0,0 +1,42 @@
+{
+  "name": "punktfunk-decky",
+  "version": "0.0.1",
+  "description": "SteamOS / Steam Deck Gaming-Mode launcher for the punktfunk streaming client.",
+  "type": "module",
+  "scripts": {
+    "build": "rollup -c",
+    "watch": "rollup -c -w",
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [
+    "decky",
+    "steam-deck",
+    "punktfunk",
+    "game-streaming"
+  ],
+  "author": "enrico",
+  "license": "BSD-3-Clause",
+  "dependencies": {
+    "@decky/api": "^1.1.3",
+    "react-icons": "^5.3.0",
+    "tslib": "^2.7.0"
+  },
+  "devDependencies": {
+    "@decky/rollup": "^1.0.2",
+    "@decky/ui": "^4.11.0",
+    "@rollup/rollup-linux-x64-musl": "^4.53.3",
+    "@types/react": "19.1.1",
+    "@types/react-dom": "19.1.1",
+    "@types/webpack": "^5.28.5",
+    "rollup": "^4.53.3",
+    "typescript": "^5.6.2"
+  },
+  "pnpm": {
+    "peerDependencyRules": {
+      "ignoreMissing": [
+        "react",
+        "react-dom"
+      ]
+    }
+  }
+}