feat(mcp-server): bring the web app's drawing knowledge to MCP

- Add a drawing guide adapted from the web system prompt (layout, edge
  routing, styles, minimal style, editing rules), returned by
  start_session, a new get_drawing_guide tool and the diagram-workflow prompt
- Add get_shape_library with the 30 icon libraries; the build copies
  docs/shape-libraries into dist and CI checks the packed files
- Accept bare mxCell lists in create_new_diagram and add_page; the server
  adds the wrapper and root cells
- Send server instructions, shorten create_new_diagram's description to
  fit Claude Code's 2,048 character limit, and annotate every tool
- Fix dead links and the totals in docs/shape-libraries/README.md

.github/workflows/publish-mcp.yml

@@ -62,6 +62,10 @@ jobs:
         if: steps.version.outputs.publish == 'true'
         run: npm test
 
+      - name: Build and check package contents
+        if: steps.version.outputs.publish == 'true'
+        run: npm run build && npm run check-package
+
       - name: Publish to npm
         if: steps.version.outputs.publish == 'true'
         run: npm publish

.github/workflows/test.yml

@@ -38,6 +38,10 @@ jobs:
       - name: Run MCP server unit tests
         run: npm --prefix packages/mcp-server test
 
+      # Tests run from src/, so check the built npm package separately
+      - name: Build MCP server and check package contents
+        run: npm --prefix packages/mcp-server run build && npm --prefix packages/mcp-server run check-package
+
   e2e:
     name: E2E Tests
     runs-on: ubuntu-latest