feat(alliances): custom alliance duration lobby control (#4522)

## Description:

Replaces the "Disable alliances" toggle in the host and single-player
lobbies with a "Custom alliances" control: a toggle plus a minutes input
(0 to 15, step 1).

- 0 minutes disables alliances, same behavior as the old toggle.
- 1 to 15 sets the alliance duration in minutes.

How it works:

- Adds one game-config field, `customAllianceDuration` (minutes).
- `Config.allianceDuration()` uses it when set (and falls back to the
existing 5 minute default), and `Config.disableAlliances()` returns true
when it is 0.
- The legacy `disableAlliances` boolean is still read, so older/archived
configs keep working.
- Validation reuses the existing `parseBoundedIntegerFromInput` and
`toggle-input-card` helpers, so it behaves like the other numeric lobby
options (spawn immunity, max timer).
- The join-lobby screen shows "Alliances: {x}m", or "Alliances:
Disabled" at 0.

<img width="279" height="145" alt="image"
src="https://github.com/user-attachments/assets/5a608e18-3811-4eef-a3a6-9344aaf667fe"
/>
<img width="270" height="152" alt="image"
src="https://github.com/user-attachments/assets/9d8a4d30-51e7-4e82-8ce0-121b12af1c61"
/>
<img width="270" height="144" alt="image"
src="https://github.com/user-attachments/assets/a65b20fb-0db5-4657-a964-880fad7c864e"
/>


## 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

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

zixer._

src/client/components/ToggleInputCard.ts

@@ -15,6 +15,9 @@ export class ToggleInputCard extends LitElement {
   @property({ attribute: false }) inputValue?: number | string;
   @property({ attribute: false }) inputAriaLabel?: string;
   @property({ attribute: false }) inputPlaceholder?: string;
+  // Optional hint shown under the input when its value is 0 (e.g. "Disabled"),
+  // so a 0 that means "off" isn't cryptic.
+  @property({ attribute: false }) zeroLabel?: string;
   @property({ attribute: false }) defaultInputValue?: number | string;
   @property({ attribute: false }) minValidOnEnable?: number;
   @property({ attribute: false }) onToggle?: (
@@ -157,6 +160,15 @@ export class ToggleInputCard extends LitElement {
             @change=${this.onChange}
             @keydown=${this.onKeyDown}
           />
+          ${this.checked &&
+          this.zeroLabel !== undefined &&
+          this.toOptionalNumber(this.inputValue) === 0
+            ? html`<div
+                class="pointer-events-none absolute left-0 right-0 top-full mt-0.5 text-center text-[10px] leading-none text-white/70"
+              >
+                ${this.zeroLabel}
+              </div>`
+            : nothing}
         </div>
       </div>
     `;