feat(console): add the standalone Dolphin emulator

The libretro dolphin core lags upstream on compatibility in the same way
LRPS2 does, so install pkgs.dolphin-emu next to pkgs.pcsx2 and run
GameCube and Wii titles through it. The cores stay for the sake of a
single frontend and a shared save/state layout.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/hosts/console.md

@@ -124,11 +124,11 @@ The greeter is **Dvorak**, like every other host here (`modules/sway.nix` forces
 `XKB_DEFAULT_VARIANT=dvorak` on cage). Only relevant if someone else has to type
 a password.
 
-### Adding RetroArch, PCSX2 and Clone Hero to Big Picture
+### Adding non-Steam titles to Big Picture
 
-All three are installed system-wide but are not Steam titles. Added as Steam
-shortcuts they appear in Big Picture and inherit Steam Input, so the controller
-works in them without further configuration.
+RetroArch, PCSX2, Dolphin and Clone Hero are installed system-wide but are not
+Steam titles. Added as Steam shortcuts they appear in Big Picture and inherit
+Steam Input, so the controller works in them without further configuration.
 
 Steam's own **Games → Add a Non-Steam Game** is the documented route and is also
 the one that tends not to work. Both that dialog's **Browse** button and the
@@ -156,6 +156,7 @@ Independent of the dialog, `steamtinkerlaunch` writes `shortcuts.vdf` directly:
 # Steam must be closed -- it rewrites shortcuts.vdf on exit.
 steamtinkerlaunch addnonsteamgame -an="RetroArch"  -ep="$(command -v retroarch)"
 steamtinkerlaunch addnonsteamgame -an="PCSX2"      -ep="$(command -v pcsx2-qt)"
+steamtinkerlaunch addnonsteamgame -an="Dolphin"    -ep="$(command -v dolphin-emu)"
 steamtinkerlaunch addnonsteamgame -an="Clone Hero" -ep="$(command -v clonehero)"
 ```
 
@@ -221,11 +222,12 @@ cores lag on compatibility and are the first place to look when a GameCube, Wii
 or PS2 title misbehaves.
 
 That has already happened for PS2: the LRPS2 core was not good enough in
-practice, so **standalone `pkgs.pcsx2` is installed** in `gaming.nix` alongside
-the core and is what PS2 titles should be run through. `pkgs.dolphin-emu` is not
-installed; add it the same way if GameCube or Wii turns out to need it.
+practice. **`pkgs.pcsx2` and `pkgs.dolphin-emu` are both installed** in
+`gaming.nix` alongside their cores, and are what PS2, GameCube and Wii titles
+should be run through. The cores stay for the sake of a single frontend and a
+shared save/state layout.
 
-Both are controller-driven and can be added to Big Picture the same way as
+Both are controller-driven and are added to Big Picture the same way as
 RetroArch. The hardware is not the limit here — a GTX 1070 and a Haswell i7 run
 PS2 and Wii comfortably.
 
@@ -278,7 +280,7 @@ once, in their own UIs:
 - **Steam** — Settings → Storage → the `+` control → add `/srv/games/steam` as a
   library folder. Games installed there survive a reinstall of the OS. That
   picker is the broken one described under
-  [Adding RetroArch, PCSX2 and Clone Hero to Big Picture](#adding-retroarch-pcsx2-and-clone-hero-to-big-picture);
+  [Adding non-Steam titles to Big Picture](#adding-non-steam-titles-to-big-picture);
   when it comes up blank, use Steam's own console instead — open Steam with
   `steam -console`, pick the **CONSOLE** tab and run:
 

hosts/Console/gaming.nix

@@ -246,6 +246,10 @@ in
   environment.systemPackages = [
     retroarch
     pkgs.clonehero
+    # Standalone GameCube/Wii and PS2, alongside the libretro cores of the same
+    # name: upstream effort goes into these builds, so they are what the two
+    # heaviest systems should actually be run through.
+    pkgs.dolphin-emu
     pkgs.pcsx2
     pkgs.dualsensectl # DualSense LED/battery/mic control from the shell
     # Writes shortcuts.vdf from the shell. Steam's own "Add a Non-Steam Game"