Homepage update & add 3 public lobbies (#3191)

## Description:

Update UI 
check https://homepageupdate.openfront.dev/ 

Improved mobile UI (now fills whole screen for all modals) e.g.:
<img width="432" height="852" alt="image"
src="https://github.com/user-attachments/assets/56de40af-4137-4c57-96b7-3910c9a665b8"
/>

Converted PublicLobby to be "GameModeSelector" to get a nicer 4x4 grid
div, where <GameModeSelector> now handles all the username validation
now (removed redundant code from modals such as matchmaking) also fixed
a bug where someone could have "[XX] X" as thier username (when the
minimum should be 3 chars for their name)

Now visually displays the 3 lobbies ffa/team/special (which is a
continuation from the work done in: #3196 )
<img width="818" height="563" alt="image"
src="https://github.com/user-attachments/assets/a15cd31b-6061-4fb8-83ee-ffde6225cfa7"
/>

updated the background:
<img width="1919" height="807" alt="image"
src="https://github.com/user-attachments/assets/358a7434-51b8-4540-baf2-d1be05053c44"
/>



slightly updated the glassy-look to be less glassy:
<img width="825" height="729" alt="image"
src="https://github.com/user-attachments/assets/1801871b-bbf8-43db-ac53-489337ae80a5"
/>



## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

w.o.n

src/client/FlagInput.ts

@@ -84,7 +84,7 @@ export class FlagInput extends LitElement {
     return html`
       <button
         id="flag-input"
-        class="flag-btn p-0! m-0 border-0 w-full h-full flex cursor-pointer justify-center items-center focus:outline-none focus:ring-0 transition-all duration-200 hover:scale-105 bg-slate-900/80 hover:bg-slate-800/80 active:bg-slate-800/90 rounded-lg overflow-hidden"
+        class="flag-btn p-0 m-0 border-0 w-full h-full flex cursor-pointer justify-center items-center focus:outline-none focus:ring-0 transition-all duration-200 hover:scale-105 bg-[color-mix(in_oklab,var(--frenchBlue)_75%,black)] hover:brightness-[1.08] active:brightness-[0.95] rounded-lg overflow-hidden"
         title=${buttonTitle}
         @click=${this.onInputClick}
       >
@@ -94,7 +94,7 @@ export class FlagInput extends LitElement {
         ></span>
         ${showSelect
           ? html`<span
-              class="text-[10px] font-black text-white/40 uppercase leading-none break-words w-full text-center px-1"
+              class="text-[10px] font-black text-white uppercase leading-none break-words w-full text-center px-1"
             >
               ${translateText("flag_input.title")}
             </span>`