allow alliance extension Fixes #491 (#1314)

## Description:

About 30s before an alliance is about to expire, both players receive a
prompt to extend the alliance. If both players agree the alliance is
extended.

## 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
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

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

evan

src/client/graphics/layers/PlayerPanel.ts

@@ -176,11 +176,9 @@ export class PlayerPanel extends LitElement implements Layer {
       if (myPlayer !== null && myPlayer.isAlive()) {
         this.actions = await myPlayer.actions(this.tile);
 
-        if (this.actions?.interaction?.allianceCreatedAtTick !== undefined) {
-          const createdAt = this.actions.interaction.allianceCreatedAtTick;
-          const durationTicks = this.g.config().allianceDuration();
-          const expiryTick = createdAt + durationTicks;
-          const remainingTicks = expiryTick - this.g.ticks();
+        if (this.actions?.interaction?.allianceExpiresAt !== undefined) {
+          const expiresAt = this.actions.interaction.allianceExpiresAt;
+          const remainingTicks = expiresAt - this.g.ticks();
 
           if (remainingTicks > 0) {
             const remainingSeconds = Math.max(