feat(fonts): update Font Awesome from v6 to v7

[Bad3r]

Context

Font Awesome 7 was released and is now available in nixpkgs as font-awesome_7. The current configuration uses Font Awesome 6, which should be upgraded to maintain compatibility with upstream projects.

Related Upstream Issue

• Font Awesome 7 support greshake/i3status-rust#2202 - Font Awesome 7 support

Per the upstream discussion, the awesome6 icon set in i3status-rust is fully compatible with Font Awesome 7 fonts. Only the font package and fontconfig name references need updating.

Changes Required

modules/system76/fonts.nix

• Update package reference (line 26):

  - font-awesome_6
  + font-awesome_7

• Update fontconfig serif font names (lines 37-38):

  - "Font Awesome 6 Free"
  - "Font Awesome 6 Brands"
  + "Font Awesome 7 Free"
  + "Font Awesome 7 Brands"

• Update fontconfig sansSerif font names (lines 44-45):

  - "Font Awesome 6 Free"
  - "Font Awesome 6 Brands"
  + "Font Awesome 7 Free"
  + "Font Awesome 7 Brands"

• Update fontconfig monospace font names (lines 52-53):

  - "Font Awesome 6 Free"
  - "Font Awesome 6 Brands"
  + "Font Awesome 7 Free"
  + "Font Awesome 7 Brands"

Acceptance Criteria

• System builds successfully with font-awesome_7
• i3status-rust icons render correctly (battery, wifi, volume, etc.)
• No visual regressions in the status bar