2661 PR 2/3 Warship Port Healing, Docking Capacity, and Waiting Behavior (#3499)

Part of [#2661](https://github.com/openfrontio/OpenFrontIO/issues/2661)
(split into 3 PRs so they are not too large..)

## Description:

Part 2/3 of
[#2661](https://github.com/openfrontio/OpenFrontIO/issues/2661).

This PR adds port-based healing and docking behavior:
- Passive healing near friendly ports
- Active docked healing pool scaled by port level and shared across
docked ships
- Docking radius and capacity-by-port-level behavior
- Waiting behavior near full ports until a slot opens
- Auto-undock once fully healed

For the active healing, it works like `ActiveHeal = (PortLevel * 5) /
DockedShipsAtThatPort`
Ex:
1 ship at level 1 port -> +5 HP/tick
1 ship at level 2 port → +10 HP/tick
2 ships at level 3 port → +7.5 HP/tick each

Includes regression tests covering healing math and docking/waiting
behavior.

## 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:

zixer._

src/core/game/UnitImpl.ts

@@ -221,11 +221,18 @@ export class UnitImpl implements Unit {
   }
 
   modifyHealth(delta: number, attacker?: Player): void {
-    this._health = withinInt(
+    const previousHealth = this._health;
+    const nextHealth = withinInt(
       this._health + toInt(delta),
       0n,
       toInt(this.info().maxHealth ?? 1),
     );
+
+    if (nextHealth === previousHealth) {
+      return;
+    }
+
+    this._health = nextHealth;
     this.mg.addUpdate(this.toUpdate());
     if (this._health === 0n) {
       this.delete(true, attacker);