Harden fulltext job failure handling

[himynamesdave]

Summary

• harden fulltext job persistence so per-item save failures remain item-level failures
• truncate overlong FulltextJob error metadata before database save to avoid varchar(1500) job aborts
• expand h4f and task coverage for fetch/parse edge cases and error handling
• bump package version to 1.2.13

Testing

• python3 -m py_compile history4feed/app/models.py
• python3 -m py_compile tests/src/test_models.py
• python3 -m py_compile tests/src/test_h4f_scripts/test_h4f__fetch.py
• python3 -m py_compile tests/src/test_h4f_scripts/test_h4f__parse.py
• python3 -m py_compile tests/src/test_h4f_scripts/test_tasks.py

Notes

• full pytest was not run in this environment

[codecov]

Codecov Report

❌ Patch coverage is 96.33028% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
history4feed/app/models.py	55.55%	3 Missing and 1 partial ⚠️

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