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

AGENTS.md

@@ -27,7 +27,7 @@ nix build .#nixosConfigurations.cryodev-pi.config.system.build.sdImage
 # Format code (required before committing)
 nix fmt
 
-# Run all checks (lint, formatting, deploy-rs validation)
+# Run all checks (lint, formatting)
 nix flake check
 
 # Quick evaluation test (faster than full build)
@@ -46,14 +46,17 @@ nix develop
 # Deploy all hosts via deploy app (uses deploy.json)
 nix run .#deploy
 
-# Deploy to cryodev-main via deploy-rs
-nix run github:serokell/deploy-rs -- .#cryodev-main
+# Deploy a specific host
+nix run .#deploy -- -n cryodev-main
 
 # Manual deployment via SSH
 NIX_SSHOPTS="-p 2299" nixos-rebuild switch --flake .#<hostname> \
   --target-host <user>@<ip> --sudo --ask-sudo-password
 ```
 
+> **Note:** Both hosts use Comin for automatic pull-based deployment.
+> Manual deployment is only needed for the initial setup or emergencies.
+
 ### Apps
 
 ```bash
@@ -200,7 +203,7 @@ services.nginx.enable = lib.mkDefault true;
 
 | Host | Strategy | Trigger |
 |------|----------|---------|
-| `cryodev-main` | Push via deploy-rs | Forgejo Actions on push to main |
+| `cryodev-main` | Pull via Comin | Automatic polling |
 | `cryodev-pi` | Pull via Comin | Automatic polling |
 | SD Images | Built in CI | Push to main (for Pi hosts) |