Add IDE integration: VS Code extension, LSP design and prototype

[godofecht]

What

First increment of IDE tooling for authoring azazel project.cue, in a new ide/ directory.

VS Code extension (ide/vscode/, plain JS, no npm deps):

• CUE syntax grammar highlighting #Module fields (kind, root, deps, profile, link) and their enum values.
• Inline diagnostics: runs cue export -e build on open and save, surfaces errors inline (bad enums, wrong types, unknown/missing fields). Missing-field errors cue can only pin to schema.cue are re-homed onto the edited file.
• Commands: "Azazel: Generate build_spec", "Azazel: Validate project.cue". Settings for cue path, validate-on-save, gen script.

Language server (ide/DESIGN.md + ide/server/):

• DESIGN.md specifies completion from schema.cue, hover docs, go-to-definition for deps, and the two graph cross-checks (a deps naming an unknown module; a module absent from export.cue's _modules).
• A dependency-free stdio LSP prototype that publishes cue diagnostics, sharing the exact diagnostic engine with the extension so they never drift.

Verification

• node --check on all JS, JSON.parse on all manifests: pass.
• LSP prototype runs end to end (initialize, validate a clean package, publish diagnostics).
• Manual VS Code test (F5 Extension Development Host) documented in ide/vscode/README.md.

Follow-ups

Implement completion/hover/go-to-definition per DESIGN.md; add the graph cross-checks; optionally wire the extension to the LSP via vscode-languageclient once those exist.

🤖 Generated with Claude Code