fix: resolve rebase conflicts from AI generation merge (#21)

* Add AI-powered spec generation and LOC coverage tracking

- Add ai module for generating specs via external AI commands (e.g. claude, ollama)
- Support flat-file module discovery alongside subdirectory-based modules
- Track lines-of-code coverage in addition to file coverage
- Add --ai flag to generate command with fallback to template on failure
- Add ai_command and ai_timeout config fields to SpecSyncConfig
- Improve generate command to work when no specs exist yet
- Filter empty spec directories from module detection

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* style: apply rustfmt formatting

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 0xLeif