Improve package tool selection in truncated catalogs

[jlitola]

Summary

• lead five package MCP descriptions with distinct natural-question triggers inside the first 80 characters
• document the Claude Desktop-specific discovery evidence and the standalone prefix design contract
• lock exact package prefixes and catalog-wide prefix uniqueness in tests
• add a RubyGems routing workload and record descriptor-only Luna/Haiku observations
• add patch release fragments for both githits and @githits/mcp

Validation

• bun test — 3,283 passed, 0 failed
• bun run build
• bun run plugins:generate
• bun run plugins:check
• bun run smoke:cli
• bun run smoke:mcp
• bun test scripts/agent-eval.test.ts — 77 passed, 0 failed
• descriptor-only Luna-low and Haiku package workloads, including a RubyGems canary
• Biome and git diff --check

Review

The internal Codex reviewer completed a clean final pass. Claude Opus completed the three-round review loop; all accepted findings were fixed and verified. The final round's low-severity uniqueness assertion was added and the full validation suite was rerun.

Coordination

The hosted backend must mirror the exact tool descriptions before public release, as documented in docs/implementation/tools.md.