Configurable immunity timer (#2763)

## Description:

Resolve discussions about stalled PR
https://github.com/openfrontio/OpenFrontIO/pull/2460

<img width="724" height="348" alt="image"
src="https://github.com/user-attachments/assets/c2c9fa79-cace-431a-9ca4-b3656612fa9d"
/>

Changes:
- Added a `Player::canAttackPlayer(other)` function to determine whether
a player can be attacked.
- This function is now used in most places where a fight can occur:
    - AttackExecution (land attacks)
    - Naval invasion
    - Warship fight
- Nukes can't be thrown during the truce
- Immunity only affect human players. Nations and bot will fight as
usual, and can be fought against.
- The immunity timer uses minutes in the modal window.

UI:

- The immunity phase is displayed with a timer bar at the top. This is
from the original PR, to be discussed if it's not deemed visible enough:

<img width="632" height="215" alt="image"
src="https://github.com/user-attachments/assets/f5ab9aa0-bd4f-4503-b8d6-b40b121fba65"
/>


## 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:

IngloriousTom

---------

Co-authored-by: newyearnewphil <git@nynp.dev>

src/client/graphics/layers/ImmunityTimer.ts

@@ -0,0 +1,93 @@
+import { LitElement, html } from "lit";
+import { customElement } from "lit/decorators.js";
+import { GameMode } from "../../../core/game/Game";
+import { GameView } from "../../../core/game/GameView";
+import { Layer } from "./Layer";
+
+@customElement("immunity-timer")
+export class ImmunityTimer extends LitElement implements Layer {
+  public game: GameView;
+
+  private isVisible = false;
+  private isActive = false;
+  private progressRatio = 0;
+
+  createRenderRoot() {
+    this.style.position = "fixed";
+    this.style.top = "0";
+    this.style.left = "0";
+    this.style.width = "100%";
+    this.style.height = "7px";
+    this.style.zIndex = "1000";
+    this.style.pointerEvents = "none";
+    return this;
+  }
+
+  init() {
+    this.isVisible = true;
+  }
+
+  tick() {
+    if (!this.game || !this.isVisible) {
+      return;
+    }
+
+    const showTeamOwnershipBar =
+      this.game.config().gameConfig().gameMode === GameMode.Team &&
+      !this.game.inSpawnPhase();
+
+    this.style.top = showTeamOwnershipBar ? "7px" : "0px";
+
+    const immunityDuration = this.game.config().spawnImmunityDuration();
+    const spawnPhaseTurns = this.game.config().numSpawnPhaseTurns();
+
+    if (immunityDuration <= 5 * 10 || this.game.inSpawnPhase()) {
+      this.setInactive();
+      return;
+    }
+
+    const immunityEnd = spawnPhaseTurns + immunityDuration;
+    const ticks = this.game.ticks();
+
+    if (ticks >= immunityEnd || ticks < spawnPhaseTurns) {
+      this.setInactive();
+      return;
+    }
+
+    const elapsedTicks = Math.max(0, ticks - spawnPhaseTurns);
+    this.progressRatio = Math.min(
+      1,
+      Math.max(0, elapsedTicks / immunityDuration),
+    );
+    this.isActive = true;
+    this.requestUpdate();
+  }
+
+  private setInactive() {
+    if (this.isActive) {
+      this.isActive = false;
+      this.requestUpdate();
+    }
+  }
+
+  shouldTransform(): boolean {
+    return false;
+  }
+
+  render() {
+    if (!this.isVisible || !this.isActive) {
+      return html``;
+    }
+
+    const widthPercent = this.progressRatio * 100;
+
+    return html`
+      <div class="w-full h-full flex z-[999]">
+        <div
+          class="h-full transition-all duration-100 ease-in-out"
+          style="width: ${widthPercent}%; background-color: rgba(255, 165, 0, 0.9);"
+        ></div>
+      </div>
+    `;
+  }
+}