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.

.gitignore

@@ -16,6 +16,8 @@ packages/*/dist
 /coverage
 /playwright-report/
 /test-results/
+packages/*/playwright-report/
+packages/*/test-results/
 
 # next.js
 /.next/