feat: add Cursor hooks support to install command

[imkarrer]

Summary

• Adds user-level Cursor hooks (~/.cursor/hooks.json + shell scripts in ~/.cursor/hooks/) that mirror all three Claude Code hook behaviors: auto-update graph after file edits, show graph status on session start, and detect changes before git commits
• All hooks fail gracefully (exit 0) since they're user-level and run for all projects, including those without code-review-graph installed
• Hooks are installed automatically when running install/init with --platform cursor or --platform all, unless --no-hooks is passed

Related Issues & PRs

• Related to support for other TUI/IDEs (e.g. OpenCode, VSCode, ..) #59 — extends multi-IDE support to Cursor hooks (not just MCP config)
• Related to autoinstaller don't work correctly #182 — this PR adds a new hooks integration (Cursor) while autoinstaller don't work correctly #182 reports format issues with the existing Claude Code hooks; the two are independent but share the hooks install area
• Related to fix: --platform target now filters skills, hooks, and instruction files (#133) #142 — PR fix: --platform target now filters skills, hooks, and instruction files (#133) #142 adds --platform filtering for hooks/skills; this PR respects the same target filtering pattern for Cursor hooks

Changes

code_review_graph/skills.py

• generate_cursor_hooks_config() — returns Cursor hooks.json config dict (version 1) with hooks for afterFileEdit, sessionStart, and beforeShellExecution
• _cursor_hook_scripts() — returns 3 shell script contents (crg-update.sh, crg-session-start.sh, crg-pre-commit.sh) that consume stdin per Cursor protocol and emit JSON on stdout
• install_cursor_hooks() — writes ~/.cursor/hooks.json (merging with existing config), creates ~/.cursor/hooks/ with executable scripts

code_review_graph/cli.py

• Calls install_cursor_hooks() in _handle_init() when target is all or cursor, gated by --no-hooks
• Added logger module-level variable for consistent logging

tests/test_skills.py

• 18 new tests across 3 test classes:
  • TestCursorHooksConfig (6 tests): config structure, event types, paths
  • TestCursorHookScripts (7 tests): script content, shebang, exit codes, commands
  • TestInstallCursorHooks (5 tests): file creation, executability, merge, idempotency, error handling

Hook Behaviors

Cursor Event	Script	Command
afterFileEdit	crg-update.sh	code-review-graph update --skip-flows
sessionStart	crg-session-start.sh	code-review-graph status
beforeShellExecution (matcher: ^git\s+commit)	crg-pre-commit.sh	code-review-graph detect-changes --brief

Testing

All 48 tests pass (30 existing + 18 new). Ruff and mypy clean.

Checklist (per CONTRIBUTING.md)

• Feature branch: feature/cursor-hooks
• Tests added for new functionality (18 new tests)
• All tests pass: uv run pytest tests/test_skills.py (48/48)
• Linting passes: ruff check with rules E, F, I, N, W
• Type checking passes: mypy --ignore-missing-imports --no-strict-optional
• Line length ≤ 100 characters
• Python 3.10+ compatible