Switch CI firmware builds to debug environments and align artifact outputs

[Copilot]

This updates CI to produce debug firmware variants across all device targets and keeps artifact upload rules aligned with those debug build outputs. Upstream development was also merged (no content delta, already current).

• Build matrix updates

  • Replaced release-like environments with debug environments in the build job matrix:
    • default → debug
    • x4-pro → x4-pro-debug
    • x4-classic → x4-classic-debug
    • sticky → sticky-debug

• Artifact mapping updates

  • Updated upload conditions to match new matrix values.
  • Updated artifact names and .pio/build/... paths to debug directories so uploads resolve correctly.

• Workflow effect

  • CI now consistently builds and publishes debug firmware artifacts for all four device families.

strategy:
  matrix:
    environment: [debug, x4-pro-debug, x4-classic-debug, sticky-debug]

- name: Upload X4 Pro firmware artifact
  if: matrix.environment == 'x4-pro-debug'
  with:
    name: firmware-x4-pro-debug
    path: .pio/build/x4-pro-debug/firmware-x4-pro.bin