tools: Add hand-written fixtures and validation for log parsers

[redbelter]

• Created test_fixtures.json with JSON, text, nginx format examples
• Created validate_fixtures.py to verify parser output correctness
• Fixed extract_service() to:
  • Match [service_name] patterns with letters/digits/hyphens/underscores
  • Skip numeric-only bracket IDs (PIDs)
  • Parse syslog format: Mon DD HH:MM:SS hostname service[pid]:
• Updated build.py f-string syntax error

Summary

Changes

Testing

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

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• I would like to request that my diagnostic build log is removed before merging

[redbelter]

Fixes #494 - $25 bounty