feat(mcp-server): canvas shell bundled from the web app's canvas with esbuild

The shell (packages/mcp-server/shell) renders DrawioFrame inside the
shared providers without the chat: its config comes from
window.__MCP_CONFIG__, the four dictionaries ship in the bundle, the
theme is kept under an mcp: localStorage key, and system fonts stand in
for the web fonts. scripts/build-shell.mjs bundles it into dist/shell
with the root's esbuild and Tailwind; check-package caps shell.js at
1.5 MB and shell.css at 300 KB.

lib/i18n/dictionaries/en.json

@@ -699,5 +699,9 @@
         "recent": "Recent diagrams",
         "drawYourself": "Start with a blank canvas",
         "openFileHint": "Keep working on a diagram you have"
+    },
+    "shell": {
+        "waiting": "Waiting for the MCP server…",
+        "toggleTheme": "Switch between light and dark"
     }
 }

lib/i18n/dictionaries/ja.json

@@ -699,5 +699,9 @@
         "recent": "最近の図",
         "drawYourself": "白紙のキャンバスから始める",
         "openFileHint": "手元の図の続きを編集"
+    },
+    "shell": {
+        "waiting": "MCP サーバーを待っています…",
+        "toggleTheme": "ライトとダークを切り替え"
     }
 }

lib/i18n/dictionaries/zh-Hant.json

@@ -699,5 +699,9 @@
         "recent": "最近的圖紙",
         "drawYourself": "從空白畫布開始",
         "openFileHint": "接著編輯已有的圖"
+    },
+    "shell": {
+        "waiting": "正在等待 MCP 伺服器…",
+        "toggleTheme": "切換淺色或深色"
     }
 }

lib/i18n/dictionaries/zh.json

@@ -699,5 +699,9 @@
         "recent": "最近的图纸",
         "drawYourself": "从空白画布开始",
         "openFileHint": "接着编辑已有的图"
+    },
+    "shell": {
+        "waiting": "正在等待 MCP 服务器…",
+        "toggleTheme": "切换浅色或深色"
     }
 }