docs: add Cursor Cloud specific dev environment instructions

[gotalab]

Adds a ## Cursor Cloud specific instructions section to AGENTS.md with development commands, project layout notes, and non-obvious caveats for future cloud agents.

Changes

• Added development command table (install, build, test, type check, run CLI)
• Documented that npm ci auto-builds via the prepare script
• Noted absence of a dedicated linter (TypeScript strict mode serves as lint)
• Clarified the CLI is a pure file-generation tool with no external dependencies

Evidence of working environment

Test output (193/193 tests pass):
test_output.log

CLI install demo output:
cli_install_demo.log

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