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>

docs/RUNBOOK.md

@@ -15,11 +15,11 @@ pnpm release:patch   # or :minor / :major
 # Requires GITHUB_TOKEN in .env
 ```
 
-CI (`release.yml`) then builds and pushes the Docker image to GHCR:
+Gitea Actions (`release.yml`) then builds and pushes the Docker image to the self-hosted registry:
 
-- `ghcr.io/ginnoir/famapp:v0.x.y`
-- `ghcr.io/ginnoir/famapp:0.x` (minor alias)
-- `ghcr.io/ginnoir/famapp:latest`
+- `registry.ginnoir.com/ginnoir/famapp:v0.x.y`
+- `registry.ginnoir.com/ginnoir/famapp:0.x` (minor alias)
+- `registry.ginnoir.com/ginnoir/famapp:latest`
 
 ## Deploying a release
 
@@ -27,7 +27,7 @@ On the home server, in `/srv/famapp/deploy/`:
 
 ```bash
 # Pin the new tag
-sed -i 's|FAMAPP_IMAGE=.*|FAMAPP_IMAGE=ghcr.io/ginnoir/famapp:v0.x.y|' .env
+sed -i 's|FAMAPP_IMAGE=.*|FAMAPP_IMAGE=registry.ginnoir.com/ginnoir/famapp:v0.x.y|' .env
 
 # Pull and restart only the app container
 docker compose pull famapp
@@ -60,7 +60,7 @@ docker compose exec famapp-db pg_isready -U famapp -d famapp
 1. Find the previous working tag in `CHANGELOG.md` or `docker images`.
 2. Pin it in `deploy/.env`:
    ```bash
-   sed -i 's|FAMAPP_IMAGE=.*|FAMAPP_IMAGE=ghcr.io/ginnoir/famapp:v0.x.y|' .env
+   sed -i 's|FAMAPP_IMAGE=.*|FAMAPP_IMAGE=registry.ginnoir.com/ginnoir/famapp:v0.x.y|' .env
    ```
 3. Restart the container:
    ```bash