test: add comprehensive tests for hook_utils and session_analyzer (TEST-001, TEST-002)

New test coverage:
- tests/test_hook_utils.py: 59 tests for shared hook utilities
  - setup_timeout/cancel_timeout (SIGALRM handling)
  - validate_file_path (security validation)
  - read_json_input (input size limits)
  - get_hook_logger (logger caching)
  - setup_logging (debug/warning configuration)

- tests/test_session_analyzer.py: 48 tests for session transcript analysis
  - parse_transcript (JSONL and plain text formats)
  - analyze/analyze_content (signal detection)
  - has_uncaptured_content (detection)
  - Novelty checking integration

All 1913 tests passing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: zircote