Stateless translation layer over Forgejo issues and comments. Auth is
forwarded verbatim (Authorization: Bearer), so Forgejo enforces per-user
permissions with no service token. Viewpoints are ifc:// URLs stored in
comment bodies; GUIDs are deterministically derived from Forgejo IDs and
are reversible without a lookup table.
Endpoints: GET/POST projects, topics, comments, viewpoints; PUT topic;
GET viewpoint snapshot (proxied through preview service).
Also adds ifc_url_to_bcf_viewpoint() to bcf.py (symmetric counterpart of
bcf_viewpoint_to_ifc_url), and fixes rate-limit state leaking between tests.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
