fix(llms): separate spec rules from safety limits

[iannuttall]

Summary

• The root cause was three local safety values presented as llms.txt v2 rules; this removes the 100-link, 100 KB, and 12-section conformance claims.
• Link checks, body reads, and agent output remain bounded, with partial or capped provenance; generation now defaults to 250 URLs and supports up to 10,000 crawl URLs.
• Regression tests cover valid large files, partial link checks, the 2 MB body limit, repeat-fetch failure, and MCP input bounds.
• Validation passed with build, typecheck, test, lint, the CLI help sweep, package dry-run, and a 10,000-page resource fixture.