Inconsistent gamepad button mapping for button2 in VIA joystick handling

[mattgodbolt]

Issue Description

There's an inconsistency in how button2 is mapped for joystick fire buttons in the VIA gamepad handling code (around line 679 in src/via.js).

Current Behavior

In SysVia.getJoysticks():

• button1: Always uses pad.buttons[10] (first gamepad, FIRE1)
• button2:
  • If 2 gamepads: Uses pad2.buttons[10] (second gamepad's FIRE1)
  • If 1 gamepad: Uses pad.buttons[11] (first gamepad's FIRE2)

Code Location

// src/via.js line ~679
button2 = button2 || (pad2 ? pad2.buttons[10].pressed : pad.buttons[11].pressed);

Expected Behavior (to be clarified)

The mapping should be consistent. Possible approaches:

1. Option A: Always use button index 10 for both scenarios
2. Option B: Always use button index 11 for button2 in both scenarios
3. Option C: Current behavior is intentional and should be documented

Context

From the gamepad mapping in gamepads.js:

• Button 10 = FIRE1
• Button 11 = FIRE2

Impact

This inconsistency may confuse users when switching between single and dual gamepad setups, as button2 maps to different physical buttons depending on the setup.

Next Steps

• Clarify if current behavior is intentional
• Add documentation explaining the mapping logic
• Consider standardizing the mapping
• Add tests to verify intended behavior

---

Note: This is existing behavior, not introduced by recent changes.