Fix Ctrl+Click for Macs, and alphabetize gitignore (#2720)

Resolves #2719 
- [X] Ran `npm run format`
- [X] Ran `npm run lint:fix`
- [X] Ran `npm test`
- [X] Manually tested fixes

## Description:

### What problem(s) was I solving?

On Mac, `Ctrl+Click` is commonly used as a substitute for right-click to
open context menus. However, in OpenFront, `Ctrl+Click` was triggering
both the context menu, AND causing an attack.

This effectively prevented Mac users from being able to ally with
bots/nations, as trying to ally would cause you to attack them.

### What changes did I make?
- `Ctrl+Click` on Mac no longer triggers an attack, allowing players to
properly interact with the alliance system

### How I implemented it

1. Added an `isMac()` method to `InputHandler` which encapsulates the
"is mac" logic, and lets it be mocked during tests
2. In the `onPointerUp` handler, added a check: if on Mac and
`ControlLeft` is held, emit a `ContextMenuEvent`, and then return
(instead of continuing to also create a `MouseUpEvent`)
3. Extracted magic numbers for mouse button checks into descriptive
helper methods (`isMiddleMouseButton`, `isNonLeftMouseButton`) for
improved code clarity
4. Added clarifying comments throughout the pointer event handlers

Last, alphabetized the `.gitignore` file and organized it into "Folders"
and "Files" sections to make it easier to read.

### How to verify it

#### Manual Testing
- [X] On a Mac, hold `Ctrl` and left-click on another nation - verify
the context menu opens (not an attack)
- [X] On a Mac, right-click should still open the context menu as
expected
- [X] On Windows/Linux, `Ctrl+Click` continue to work as before
(modifier key for build menu if configured)
- [X] Regular left-click still triggers attacks/interactions as expected

#### Automated Testing
- [x] New unit test added: `Mac Ctrl+Click Context Menu` - verifies that
`Ctrl+Click` on Mac emits `ContextMenuEvent` instead of `MouseUpEvent`

### Description for the changelog

Fixed `Ctrl+Click` on Mac to properly open the context menu instead of
triggering an attack, restoring the ability for Mac users to form
alliances with other nations.

## 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:
Terekhov

tests/InputHandler.test.ts

@@ -1,4 +1,9 @@
-import { AutoUpgradeEvent, InputHandler } from "../src/client/InputHandler";
+import {
+  AutoUpgradeEvent,
+  ContextMenuEvent,
+  InputHandler,
+  MouseUpEvent,
+} from "../src/client/InputHandler";
 import { EventBus } from "../src/core/EventBus";
 
 class MockPointerEvent {
@@ -452,4 +457,46 @@ describe("InputHandler AutoUpgrade", () => {
       spy.mockRestore();
     });
   });
+
+  describe("Mac Ctrl+Click Context Menu", () => {
+    test("should create context menu with Ctrl+Click on Mac, but not attack", () => {
+      // Mock isMac() to return true
+      vi.spyOn(inputHandler as any, "isMac").mockReturnValue(true);
+      const mockEmit = vi.spyOn(eventBus, "emit");
+
+      // Simulate ControlLeft being held
+      inputHandler["activeKeys"].add("ControlLeft");
+
+      // Simulate a pointer down first (to set pointerDown state)
+      const pointerDownEvent = new PointerEvent("pointerdown", {
+        button: 0,
+        clientX: 100,
+        clientY: 200,
+        pointerId: 1,
+      });
+      inputHandler["onPointerDown"](pointerDownEvent);
+      mockEmit.mockClear();
+
+      // Now trigger pointer up
+      const pointerUpEvent = new PointerEvent("pointerup", {
+        button: 0,
+        clientX: 100,
+        clientY: 200,
+        pointerId: 1,
+      });
+      inputHandler["onPointerUp"](pointerUpEvent);
+
+      // Verify ContextMenuEvent was emitted with correct coordinates
+      expect(mockEmit).toHaveBeenCalledTimes(1);
+      // If MouseUp is fired, that would cause an attack - which we do not want.
+      expect(mockEmit).not.toHaveBeenCalledWith(expect.any(MouseUpEvent));
+      expect(mockEmit).toHaveBeenCalledWith(expect.any(ContextMenuEvent));
+      expect(mockEmit).toHaveBeenCalledWith(
+        expect.objectContaining({
+          x: 100,
+          y: 200,
+        }),
+      );
+    });
+  });
 });