Fix spelling typos and improve code quality (#2186)

## Description:
  This PR fixes several bugs and improves code quality:

- Fix spelling typos: "recieved" → "received" in Transport.ts and
GameServer.ts
  - Fix comment typo: "isn'te" → "isn't" in TerrainLayer.ts
- Improve WebSocket cleanup in Transport.ts leaveGame() by replacing
empty onclose handler with proper
   killExistingSocket() call
- Add console.warn for image decode failures in StructureLayer.ts
instead of silent catch
  - Remove commented dead code in DevConfig.ts

  ## Testing
All 288 tests pass. Development build completes successfully. No
breaking changes.

  ## Files Changed
  - src/client/Transport.ts
  - src/server/GameServer.ts
  - src/client/graphics/layers/TerrainLayer.ts
  - src/client/graphics/layers/StructureLayer.ts
  - src/core/configuration/DevConfig.ts

## Checklist:
- [x] I have added screenshots for all UI updates (N/A - no UI changes)
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file (N/A - no user-facing text)
- [x] I have added relevant tests to the test directory (All 288
existing tests pass - no new tests needed for typo fixes)
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

  Discord: hiphex_33496

Hiphex

Co-authored-by: Claude <noreply@anthropic.com>

src/client/graphics/layers/StructureLayer.ts

@@ -138,7 +138,9 @@ export class StructureLayer implements Layer {
 
     Promise.all(
       Array.from(this.unitIcons.values()).map((img) =>
-        img.decode?.().catch(() => {}),
+        img.decode?.().catch((err) => {
+          console.warn("Failed to decode unit icon image:", err);
+        }),
       ),
     ).finally(() => {
       this.game.units().forEach((u) => this.handleUnitRendering(u));

src/client/graphics/layers/TerrainLayer.ts

@@ -49,7 +49,7 @@ export class TerrainLayer implements Layer {
     this.theme = this.game.config().theme();
     this.game.forEachTile((tile) => {
       const terrainColor = this.theme.terrainColor(this.game, tile);
-      // TODO: isn'te tileref and index the same?
+      // TODO: isn't tileref and index the same?
       const index = this.game.y(tile) * this.game.width() + this.game.x(tile);
       const offset = index * 4;
       this.imageData.data[offset] = terrainColor.rgba.r;