sway: per-host overrides via host.conf and session-env

Adds a host_sway_dotfiles mechanism mirroring host_i3_dotfiles: hosts
drop a host.conf into ~/.config/sway/ to override sway settings, and
optionally a session-env file sourced by start-sway for per-host
environment variables. The base sway/config defines $terminal and
includes ~/.config/sway/host.conf; an empty placeholder ships with the
base profile so the include never warns on hosts without overrides.

nymph gets its own host.conf wrapping alacritty in prime-run (NVIDIA
PRIME offload), bumping gaps/corner_radius, and pinning workspaces to
eDP-1 / DP-1, plus a session-env exporting SWAY_UNSUPPORTED_GPU=1 and
WLR_DRM_DEVICES for the hybrid Intel+NVIDIA setup.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

dotfiles/nymph/.config/sway/host.conf

@@ -0,0 +1,16 @@
+set $terminal ~/.local/bin/prime-run /usr/bin/alacritty
+
+gaps inner 10
+gaps outer 5
+corner_radius 10
+
+workspace 1 output eDP-1
+workspace 2 output DP-1
+workspace 3 output DP-1
+workspace 4 output DP-1
+workspace 5 output DP-1
+workspace 6 output DP-1
+workspace 7 output DP-1
+workspace 8 output DP-1
+workspace 9 output DP-1
+workspace 10 output DP-1

dotfiles/nymph/.config/sway/session-env

@@ -0,0 +1,6 @@
+export LIBVA_DRIVER_NAME=iHD
+export QT_QPA_PLATFORM=wayland
+export QT_QPA_PLATFORMTHEME=qt6ct
+export SWAY_UNSUPPORTED_GPU=1
+export WLR_DRM_DEVICES=/dev/dri/card0:/dev/dri/card1
+export WLR_NO_HARDWARE_CURSORS=1