[$40 BOUNTY] feat: add sanitized parse-error report

[shadow6427]

Summary

Resolves issue #1

Add --parse-error-report PATH CLI option to log_aggregator.py. This writes a sanitized JSON report of parse failures by file and line number, without leaking raw log payloads.

Changes

• Updated LogParser.parse to ignore empty lines.
• JSONLogParser.parse now raises ValueError with a sanitized message on JSON Decode errors.
• _parse_line catches ValueError and correctly propagates parser errors to process_file.
• _record_parse_failure correctly tracks the exact line, file, and sanitized error string.
• Added 4 test cases to test_log_aggregator.py.

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR (metadata JSON since .logd failed encryptly preflight on macOS ARM64)
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered