fix: generate valid Claude Code hook schema (closes #138)

[sebastianbreguel]

Closes #138

Problem

generate_hooks_config() emits a hooks config that Claude Code rejects with schema errors, so code-review-graph install corrupts ~/.claude/settings.json. Three bugs in the same function:

1. PreCommit is not a valid Claude Code hook event → Invalid key in record.
2. Missing inner hooks array wrapper. Each entry must have hooks: [{type: "command", command, timeout}], but the old output put command/timeout directly on the entry → hooks: Expected array, but received undefined (the exact error in the issue for SessionStart).
3. Timeouts in milliseconds instead of seconds. 5000, 3000, 10000 — the PostToolUse hook effectively had an 83-minute timeout.

Verified against the official schema: https://docs.claude.com/en/docs/claude-code/hooks

Fix

Rewrite generate_hooks_config() to match the documented schema:

"PostToolUse": [
  {
    "matcher": "Edit|Write|Bash",
    "hooks": [
      {"type": "command", "command": "code-review-graph update --quiet --skip-flows", "timeout": 5}
    ]
  }
]

• Remove the PreCommit entry (no equivalent Claude Code event; pre-commit behavior belongs in a git hook).
• Wrap PostToolUse and SessionStart handlers in hooks: [{type: "command", ...}].
• Convert timeouts from ms to seconds (5000 → 5, 3000 → 3).

Testing

• test_has_post_tool_use / test_has_session_start updated for the nested structure
• New test_does_not_emit_precommit — regression guard for this issue
• New test_all_commands_wrapped_in_inner_hooks_array — structural invariant
• Full suite: 611 passed, 5 skipped, 0 failed
• ruff check clean

[sebastianbreguel]

@tirth8205 hey! could you review this one too? it fixes the hook schema generation (issue #138)

[tirth8205]

This is a critical correctness fix — the hook schema rewrite looks solid. 4 regression tests, clean approach.

Please rebase on latest main (PR #152 just merged and touches the same skills.py file). Once rebased and CI passes, this is good to merge.

[sebastianbreguel]

@tirth8205 Rebased on latest main, conflicts resolved, CI is green. Ready to merge when you are!