refactor: clean up file locations (#48)

- Remove duplicate bilder/ directory from root (already in public/bilder/)
- Move screenshots (docker-preview, page-preview, screenshot-landingpage) to docs/
- Remove duplicate robots.txt from root (already in public/)
- Update README.md image references to docs/ path
- Update deploy workflow exclusions

.gitea/workflows/deploy-test.yml

@@ -41,9 +41,7 @@ jobs:
             --exclude='nginx.conf' \
             --exclude='eslint.config.js' \
             --exclude='package.json' \
-            --exclude='docker-preview.png' \
-            --exclude='page-preview.png' \
-            --exclude='screenshot-landingpage*' \
+            --exclude='docs/' \
             --exclude='AGENTS.md' \
             --exclude='README.md' \
             ./ /deploy/