feat(ui): dark theme redesign, fix image search and defaults

- Inline CSS in base.html (Inter, dark mode, sticky search, tabs, results)
- Remove HTMX/JS from templates; pagination via GET links
- Atmospheric side gradients + grid; wider column on large viewports
- Parse ?category= for HTML tabs (fixes Images category routing)
- Include bing_images, ddg_images, qwant_images in local_ported defaults
- Default listen port 5355; update Docker, compose, flake, README
- Favicon img uses /favicon/ proxy; preferences without inline JS

Made-with: Cursor

docker-compose.yml

@@ -8,7 +8,7 @@ services:
   kafka:
     build: .
     ports:
-      - "8080:8080"
+      - "5355:5355"
     volumes:
       - ./config.toml:/etc/kafka/config.toml:ro
     depends_on: