[00200200]

Closes #27

Summary of Changes

• Implemented lightweight stdlib Language Server Protocol (LSP) server in src/cinch/lsp.py using standard JSON-RPC 2.0 with Content-Length framing and NDJSON fallback.
• Added support for core LSP methods:
  • initialize, initialized, shutdown, exit
  • textDocument/didOpen, textDocument/didChange, textDocument/didClose
  • textDocument/completion: provides completions for schema fields (ALLOWED_KEYS), dialect names, triggers, booleans, and glob patterns.
  • textDocument/hover: provides markdown tooltips explaining harness-specific behavior and limitations.
  • textDocument/publishDiagnostics: real-time frontmatter validation flagging syntax issues, unrecognized keys (with close match suggestions), missing/invalid name (kebab-case), description length boundaries, and glob validity.
• Added cinch lsp subcommand in src/cinch/cli.py with optional --strict mode.
• Expanded key suggestions in src/cinch/schema.py for common alias mappings (variables, compatibility, params, dependencies).
• Added full unit test coverage in tests/test_lsp.py covering lifecycle, diagnostics, completion, hover, and stdio framing.

[github-actions]

👋 Thanks for opening this pull request, @00200200!

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