fix(ui): Logo to PNG, start.sh port fix, LOGIN position, Up/Down horizontal

- Logo: Use LOGO_TCK_small.png instead of SVG
- start.sh: Fix arbitrary port handling (dev:8888 now works)
- Header: Move LOGIN indicator to top-left next to logo
- NavigationButtons: Make Up/Down horizontal, match title size

start.sh

@@ -191,6 +191,9 @@ if [ $# -gt 0 ]; then
     elif [[ "$1" == preview:* ]]; then
         port="${1#preview:}"
         run_preview_server "$port"
+    elif [[ "$1" =~ ^[[:digit:]]+$ ]]; then
+        # Direct port number
+        run_dev_server "$1"
     else
         run_command "$1"
     fi