fix(examples): resolve DIST_DIR path for npm package execution (#277)

* fix(examples): resolve DIST_DIR path for npm package execution

When servers are compiled to dist/server.js and published to npm,
`import.meta.dirname` already points to dist/, so joining with "dist"
results in dist/dist/ which doesn't exist.

This fix detects whether we're running from TypeScript source or
compiled JavaScript and adjusts the path accordingly:
- From source (server.ts): use dist/ subdirectory
- From compiled (dist/server.js): use current directory

Fixes ENOENT errors like:
"ENOENT: no such file or directory, open '.../dist/dist/mcp-app.html'"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix(pdf-server): mark pdfjs-dist as external in bundle

The pdf.worker.mjs file wasn't being found when running from npm
because bun bundled pdfjs-dist but didn't include the worker file.

By marking pdfjs-dist as external, it uses the installed package
from node_modules at runtime where the worker is available.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

examples/pdf-server/package.json

@@ -14,7 +14,7 @@
     "dist"
   ],
   "scripts": {
-    "build": "tsc --noEmit && cross-env INPUT=mcp-app.html vite build && tsc -p tsconfig.server.json && bun build server.ts --outdir dist --target node && bun build main.ts --outfile dist/index.js --target node --external \"./server.js\" --banner \"#!/usr/bin/env node\"",
+    "build": "tsc --noEmit && cross-env INPUT=mcp-app.html vite build && tsc -p tsconfig.server.json && bun build server.ts --outdir dist --target node --external pdfjs-dist && bun build main.ts --outfile dist/index.js --target node --external \"./server.js\" --external pdfjs-dist --banner \"#!/usr/bin/env node\"",
     "watch": "cross-env INPUT=mcp-app.html vite build --watch",
     "serve": "bun --watch main.ts",
     "start": "cross-env NODE_ENV=development npm run build && npm run serve",