fix(mcp): restore schema descriptions and regenerate schema

[BartWaardenburg]

Summary:

• Restore the schema-driving MCP field descriptions that were trimmed too far
• Regenerate the checked-in root schema artifact

Validation:

• cargo test -p fallow-mcp converted_field_descriptions_render_in_schema -- --nocapture
• cargo test --workspace --all-targets
• git diff --check

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Fallow Benchmarks'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.50.

Benchmark suite	Current: 0983cf0	Previous: cab4ab3	Ratio
parse_single_file	64164 ns/iter (± 406)	37282 ns/iter (± 158)	1.72
dupe_detect_2x500_identical	235880 ns/iter (± 12319)	142856 ns/iter (± 1940)	1.65
dupe_detect_2x2000_identical	1072238 ns/iter (± 11644)	635362 ns/iter (± 14709)	1.69
dupe_detect_100x200_mixed	4356454 ns/iter (± 30216)	2550490 ns/iter (± 16010)	1.71
dupe_detect_100x200_mixed_focused	4383980 ns/iter (± 26791)	2576395 ns/iter (± 31927)	1.70
dupe_detect_2x5000_identical	3001302 ns/iter (± 9361)	1733310 ns/iter (± 19658)	1.73

This comment was automatically generated by workflow using github-action-benchmark.