Fix: Update Docker config to use pnpm instead of npm

- Switched from npm ci to pnpm install --frozen-lockfile
- Added corepack enable for pnpm support
- Added .dockerignore for cleaner builds

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

.dockerignore

@@ -0,0 +1,42 @@
+# Dependencies
+node_modules
+.pnpm-store
+
+# Build outputs
+.next
+out
+build
+dist
+
+# Development
+.env*.local
+.env.development
+.env.test
+
+# IDE
+.idea
+.vscode
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Git
+.git
+.gitignore
+
+# Docker
+Dockerfile*
+docker-compose*
+.dockerignore
+
+# Misc
+*.md
+!README.md
+*.log
+npm-debug.log*
+pnpm-debug.log*
+coverage
+.nyc_output