* feat: add agent description compression with lazy loading (#491)
Agent descriptions consume ~26k tokens (121KB across 27 agents). This adds
a compression library with three modes:
- catalog: metadata only (~2-3k tokens) for agent selection
- summary: metadata + first paragraph (~4-5k tokens) for routing
- full: no compression, for when agent is invoked
Includes lazy-load function to fetch full agent body on demand.
21 tests covering parsing, compression, filtering, and real agents dir.
* fix: update JSDoc to include all stats fields in buildAgentCatalog
Add compressedBytes and mode to the documented return type, matching
the actual implementation.