Add new DependencyType 'attests' for skill attestations. Enables:
Entity X attests that Entity Y has skill Z at level N.
- Add DepAttests constant to dependency types
- Add AttestsMeta struct for skill, level, date, evidence, notes
- Update IsWellKnown() to include attests
- Add test cases for the new edge type
Foundation for HOP skill portability.
Closes: bd-2papc
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Executed-By: beads/crew/dave
Rig: beads
Role: crew