chore(mcp): add playwright server pinned to nix-profile chromium

Mirrors the configuration we use across aiolabs/webapp. Sites forked
from the boilerplate inherit a browser-driving MCP server for visual
inspection, screenshots and devtools-protocol access against any URL
without needing per-project setup.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.mcp.json

@@ -3,6 +3,18 @@
     "shadcn": {
       "command": "npx",
       "args": ["shadcn-vue@latest", "mcp"]
+    },
+    "playwright": {
+      "type": "stdio",
+      "command": "npx",
+      "args": [
+        "@playwright/mcp@latest",
+        "--executable-path",
+        "/etc/profiles/per-user/padreug/bin/chromium",
+        "--caps",
+        "devtools"
+      ],
+      "env": {}
     }
   }
 }