Replace removed B2B org credit system with consumer-friendly shared
Mana pools. Members spend directly from a guild pool managed by the
Gildenmeister (owner). Supports funding from personal balance,
per-member spending limits, and credit source routing.
New endpoints: /gilden/* (guild CRUD) and /credits/guild/* (pool ops).
POST /credits/use now accepts optional creditSource for guild routing.
Delete broken b2b-journey E2E tests that tested phantom endpoints.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
