ci: publish famapp images to valhalla registry

Add Gitea Actions workflows (ci.yml, release.yml) that build and push
to registry.ginnoir.com. Disable GitHub release creation. Update all
doc/compose references from ghcr.io to registry.ginnoir.com.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -74,7 +74,7 @@ The container runs database migrations automatically on start. The first user to
 Pin `FAMAPP_IMAGE` in `deploy/.env` after the first deploy:
 
 ```
-FAMAPP_IMAGE=ghcr.io/ginnoir/famapp:v0.4.7
+FAMAPP_IMAGE=registry.ginnoir.com/ginnoir/famapp:v0.4.7
 ```
 
 ---
@@ -155,4 +155,4 @@ See [`CLAUDE.md`](CLAUDE.md) for the full architecture brief and [`docs/decision
 | Pre-deploy checklist | [`docs/tasks/09-pre-deploy-checklist.md`](docs/tasks/09-pre-deploy-checklist.md) |
 | Changelog            | [`CHANGELOG.md`](CHANGELOG.md)                                                   |
 
-Cutting a release: tag `vX.Y.Z` on `main` and push — CI builds and pushes `ghcr.io/ginnoir/famapp:vX.Y.Z` automatically.
+Cutting a release: tag `vX.Y.Z` on `main` and push — Gitea Actions builds and pushes `registry.ginnoir.com/ginnoir/famapp:vX.Y.Z` automatically.