Code review fixes, Docker, and deployment config

- Fix tsconfig: switch to ESNext/Bundler module resolution (tsx compatible)
- Sanitize file extensions against path traversal (^.[a-zA-Z0-9]+$ only)
- Sanitize Content-Disposition filename to prevent header injection
- Extract tokenCookieOptions helper to eliminate duplication across auth handlers
- Remove unused baseUrl param from fileListPage
- Add Dockerfile (multi-stage build with alpine + native tools for bcrypt)
- Add docker-compose.yml with named volume for data persistence
- Add .env.example with all environment variables documented

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/views/file-list.ts

@@ -1,7 +1,7 @@
 import { layout, escHtml } from './layout.ts';
 import type { FileRow } from '../db/files.ts';
 
-export function fileListPage(files: FileRow[], baseUrl: string): string {
+export function fileListPage(files: FileRow[]): string {
   const rows = files.length === 0
     ? '<tr><td colspan="5">No files yet. <a href="/upload">Upload one.</a></td></tr>'
     : files.map((f) => `