Export the toolkit hints and the dconf profile

The toolkit variables are the generic Wayland session contract, not
anything COSMIC-specific: Firefox on Wayland instead of XWayland, Qt
preferring the Wayland platform plugin with an xcb fallback, and Java AWT
told not to expect a reparenting window manager, without which Swing
windows come up blank or mispositioned. Leaving them out is why Qt and
Java applications behaved differently under HyprCosmic than under the
stock session on the same machine.

They are set with `:-` like the XDG lines above rather than assigned
outright, so a value already chosen in the environment survives.

The Qt platform theme stays pointed at CuteCosmic rather than being
switched to qt5ct the way HyDE would have it. This fork themes GTK,
waybar and rofi and has no Qt pipeline at all, so handing Qt applications
to qt5ct would hand them to a configuration nothing here writes; CuteCosmic
at least follows the COSMIC palette that cosmic.conf does drive. Worth
revisiting if Qt theming ever gets built.

DCONF_PROFILE is guarded, which start-cosmic's is not. Naming a profile
dconf cannot find is not a soft failure: it logs "using null configuration"
and from then on every GSettings read returns schema defaults while writes
go nowhere, so a desktop's worth of settings simply appears blank. Measured
on this machine -- `DCONF_PROFILE=cosmic` dumps 33 keys, a name that does
not resolve dumps zero. So the profile is looked for first and the variable
is only exported once found.

The bare name is used rather than an absolute path. start-cosmic gets its
prefix rewritten in at install time by the Justfile, which pins one prefix;
dconf searches /etc/dconf/profile first and XDG_DATA_DIRS after, so the
bare name finds the packaged profile under /usr/share while still letting
an administrator override it from /etc.

DCONF_PROFILE joins SSH_AUTH_SOCK in the systemd and D-Bus activation
environments, matching what start-cosmic imports.

data/start-hyprcosmic

@@ -68,6 +68,79 @@ export XDG_CURRENT_DESKTOP="${XDG_CURRENT_DESKTOP:-COSMIC}"
 export XDG_SESSION_DESKTOP="${XDG_SESSION_DESKTOP:-hyprcosmic}"
 export XDG_SESSION_TYPE="${XDG_SESSION_TYPE:-wayland}"
 
+# Toolkit hints, same set start-cosmic exports.
+#
+# These are what make non-GTK applications behave under a Wayland session at
+# all: Firefox on Wayland rather than XWayland, Qt preferring the Wayland
+# platform plugin and falling back to xcb, and Java AWT not expecting a
+# reparenting window manager (without it, Swing windows come up blank or
+# mispositioned). Nothing here is COSMIC-specific -- it is the generic Wayland
+# session contract, and leaving it out is why Qt and Java apps looked different
+# under HyprCosmic than under the stock session.
+#
+# `:-` rather than a plain assignment, matching the XDG lines above: if
+# something in the environment already made a deliberate choice, it keeps it.
+export _JAVA_AWT_WM_NONREPARENTING="${_JAVA_AWT_WM_NONREPARENTING:-1}"
+export GDK_BACKEND="${GDK_BACKEND:-wayland,x11}"
+export MOZ_ENABLE_WAYLAND="${MOZ_ENABLE_WAYLAND:-1}"
+export QT_QPA_PLATFORM="${QT_QPA_PLATFORM:-wayland;xcb}"
+export QT_AUTO_SCREEN_SCALE_FACTOR="${QT_AUTO_SCREEN_SCALE_FACTOR:-1}"
+export QT_ENABLE_HIGHDPI_SCALING="${QT_ENABLE_HIGHDPI_SCALING:-1}"
+
+# Qt platform theme: CuteCosmic if it is installed, qt6ct/qt5ct if not.
+#
+# Kept pointing at COSMIC's theme rather than HyDE's, because this fork themes
+# GTK/waybar/rofi and has no Qt pipeline: switching to qt5ct here would hand Qt
+# apps to a configuration nothing in this project writes. CuteCosmic at least
+# follows the COSMIC palette that cosmic.conf does drive.
+if [[ -z "${QT_QPA_PLATFORMTHEME:-}" ]]; then
+    export QT_QPA_PLATFORMTHEME=cosmic
+    for qt_plugin_path in /usr/lib{*,/*}/qt6/plugins; do
+        if [[ -f "${qt_plugin_path}/platformthemes/libcutecosmictheme.so" ]]; then
+            export QT_QPA_PLATFORMTHEME=cosmic
+            break
+        elif [[ -f "${qt_plugin_path}/platformthemes/libqt6ct.so" ]] ||
+             [[ -f "${qt_plugin_path}/platformthemes/libqt5ct.so" ]]; then
+            # Keep looking; CuteCosmic later in the glob still wins.
+            # "qt5ct" is the value both qt5ct and qt6ct answer to.
+            export QT_QPA_PLATFORMTHEME=qt5ct
+        fi
+    done
+    unset qt_plugin_path
+fi
+
+# dconf profile, which is where COSMIC's own settings live.
+#
+# The profile file -- `user-db:cosmic` layered above the usual user and system
+# databases -- is shipped by the cosmic-session package, under
+# /usr/share/dconf/profile/cosmic on Fedora.
+#
+# Naming a profile that cannot be found is not a soft failure. dconf logs
+# "using null configuration" and then every GSettings read falls back to schema
+# defaults while writes go nowhere: a whole desktop's settings, apparently
+# blank. Measured here -- a missing profile dumps zero keys where the default
+# profile dumps a full set -- which is why this is guarded and start-cosmic's
+# unconditional export is not copied.
+#
+# The bare name is used rather than an absolute path. start-cosmic has its
+# prefix rewritten in at install time by the Justfile, but dconf searches
+# /etc/dconf/profile first and XDG_DATA_DIRS after, so the bare name keeps an
+# administrator's /etc override working instead of pinning one prefix.
+dconf_profile_found=""
+IFS=: read -r -a xdg_data_dirs <<<"${XDG_DATA_DIRS:-/usr/local/share:/usr/share}" || :
+for dir in /etc "${xdg_data_dirs[@]}"; do
+    if [[ -f "${dir}/dconf/profile/cosmic" ]]; then
+        dconf_profile_found=1
+        break
+    fi
+done
+if [[ -n "${dconf_profile_found}" ]]; then
+    export DCONF_PROFILE=cosmic
+else
+    echo "start-hyprcosmic: no dconf profile 'cosmic' found; leaving DCONF_PROFILE unset" >&2
+fi
+unset dconf_profile_found xdg_data_dirs dir
+
 # gnome-keyring, and the SSH agent it provides.
 #
 # PAM starts the daemon at login but brings up only its `control` socket, so
@@ -155,7 +228,8 @@ if command -v systemctl >/dev/null; then
     #
     # `||:` throughout -- losing a portal is bad, refusing to log in is worse.
     systemctl --user import-environment \
-        XDG_CURRENT_DESKTOP XDG_SESSION_DESKTOP XDG_SESSION_TYPE SSH_AUTH_SOCK ||:
+        XDG_CURRENT_DESKTOP XDG_SESSION_DESKTOP XDG_SESSION_TYPE \
+        DCONF_PROFILE SSH_AUTH_SOCK ||:
 fi
 
 # Same variables again for dbus-daemon's own activation environment, which
@@ -167,7 +241,8 @@ fi
 # login arrives with DBUS_SESSION_BUS_ADDRESS already set.
 if [[ -n "${DBUS_SESSION_BUS_ADDRESS}" ]] && command -v dbus-update-activation-environment >/dev/null; then
     dbus-update-activation-environment \
-        XDG_CURRENT_DESKTOP XDG_SESSION_DESKTOP XDG_SESSION_TYPE SSH_AUTH_SOCK ||:
+        XDG_CURRENT_DESKTOP XDG_SESSION_DESKTOP XDG_SESSION_TYPE \
+        DCONF_PROFILE SSH_AUTH_SOCK ||:
 fi
 
 # cosmic-session takes the compositor to launch as its first argument