remove all deploy-rs references from docs and config

- Update README, AGENTS.md, docs/index.md, docs/deployment/cd.md,
  docs/services/forgejo.md: replace deploy-rs with Comin everywhere
- Fix repo URL references (cryodev-server -> cryodev)
- Fix forgejo admin create command to use shell alias
- Rewrite cd.md for Comin-only deployment

docs/services/forgejo.md

@@ -75,44 +75,23 @@ forgejo-runner:
 
 ## CI/CD Workflows
 
-### deploy-rs Workflow
+CI runs on every push to `main` via Forgejo Actions:
 
-`.forgejo/workflows/deploy.yaml`:
+1. **flake-check** -- validates the flake
+2. **build-hosts** -- builds all host configurations
 
-```yaml
-name: Deploy
-on:
-  push:
-    branches: [main]
-
-jobs:
-  deploy:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      
-      - name: Install Nix
-        uses: cachix/install-nix-action@v24
-        
-      - name: Deploy
-        env:
-          SSH_PRIVATE_KEY: ${{ secrets.DEPLOY_SSH_KEY }}
-        run: |
-          mkdir -p ~/.ssh
-          echo "$SSH_PRIVATE_KEY" > ~/.ssh/id_ed25519
-          chmod 600 ~/.ssh/id_ed25519
-          nix run .#deploy
-```
+Deployment is handled by **Comin** (pull-based), not by CI.
+See [CD documentation](../deployment/cd.md) for details.
 
 ## Administration
 
 ### Create Admin User
 
 ```bash
-sudo -u forgejo forgejo admin user create \
-  --username admin \
-  --password changeme \
-  --email admin@cryodev.xyz \
+forgejo admin user create \
+  --username <benutzername> \
+  --email <email>@<domain> \
+  --password <passwort> \
   --admin
 ```