server : add themes + favicon (#6848)

* Added themes support with two sample themes and a favicon.

* Newline

* Newline

* Newline

* Trailing whitespace

* Increased opacity for contrast

* Increase opacity.

Check actions cancelled for some other priority job and I can't seem to manually re-run them, so MOAR OPACITY

* Opacity action trigger.

Trying to re-trigger the cancelled action.

* One more opacity adjustment

This Actions pipeline is failing for random issues.

* Delete examples/server/themes/buttons_top/completion.js

This will be served from the static string built-in to server.

* Delete examples/server/themes/buttons_top/index.js

This will be served from the static string built-in to server.

* Delete examples/server/themes/wild/completion.js

This will be served from the static string built-in to server.

* Delete examples/server/themes/buttons_top/json-schema-to-grammar.mjs

This will be served from the static string built-in to server.

* Delete examples/server/themes/wild/index.js

This will be served from the static string built-in to server.

* Delete examples/server/themes/wild/json-schema-to-grammar.mjs

This will be served from the static string built-in to server.

* Replaced underscore.

examples/server/themes/README.md

@@ -0,0 +1,5 @@
+# LLaMA.cpp Server Wild Theme
+
+Simple themes directory of sample "public" directories. To try any of these add --path to your run like `server --path=wild`.
+
+![image](wild/wild.png)

examples/server/themes/buttons-top/README.md

@@ -0,0 +1,7 @@
+# LLaMA.cpp Server Buttons Top Theme
+
+Simple tweaks to the UI. Chat buttons at the top of the page instead of bottom so you can hit Stop instead of chasing it down the page.
+
+To use simply run server with `--path=themes/buttons_top`
+
+![image](buttons_top.png)