refactor: move images into deploy-static-site, root CI workflow

- deploy-static-site/images/flake.nix: moved from images/flake.nix
- .forgejo/workflows/build-static-server.yaml: moved from images/.forgejo/
  (Forgejo only picks up workflows from repo root .forgejo/workflows/)
- updated path reference in build workflow

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.forgejo/workflows/build-static-server.yaml

@@ -1,20 +1,20 @@
-name: Build and Push Images
+name: Build and Push static-server Image
 
 on:
   push:
     branches: [main]
     paths:
-      - 'images/flake.nix'
+      - 'deploy-static-site/images/flake.nix'
   workflow_dispatch:
 
 jobs:
-  build-static-server:
+  build:
     runs-on: nix
     steps:
       - uses: actions/checkout@v4
 
       - name: Build static-server image
-        run: nix build ./images#staticServer --out-link result-static-server
+        run: nix build ./deploy-static-site/images#staticServer --out-link result-static-server
 
       - name: Push to registry
         run: |