feat: add dockerfile language server

[edlsh]

Summary

Add Dockerfile LSP support via dockerfile-language-server-nodejs.

Changes

• Add DockerfileLS LSP server with auto-install from npm
• Supports files named Dockerfile and files with .dockerfile extension

Features

• Code completion for Dockerfile instructions (FROM, RUN, COPY, etc.)
• Hover documentation
• Diagnostics for syntax errors
• Formatting support
• Go-to-definition
• Document symbols
• Rename support

Note

Files like Dockerfile.dev or Dockerfile.prod are not supported due to extension-based matching limitations. Pattern matching support would be needed (see #2182).

Tests Run

• bun run typecheck (opencode package) - passed
• bun test - 255 passed, 1 skipped, 0 failed
• Verified extension matching logic with path.parse() for:
  • Dockerfile → matches via filename fallback
  • app.dockerfile → matches via .dockerfile extension
• Verified asset naming against dockerfile-language-server-nodejs npm package

[rekram1-node]

/review

[github-actions[bot]]

lgtm