Add power profiles to Power & Lock

The same Power Saver / Balanced / Performance choice GNOME's Power panel
offers, and the daemon behind it was already running here -- it simply
had no control anywhere in Panama. This machine has been sitting on
"performance" with nothing to say so.

Talks to the net.hadess.PowerProfiles interface rather than to a binary.
Fedora 44 implements it with tuned-ppd instead of power-profiles-daemon,
and powerprofilesctl is not installed at all, so anything shelling out
to that command would have found nothing while the service was right
there. Setting a profile needs no privileges: the daemon accepts a
property write from the active session user.

Not a stored preference. The daemon owns the profile, it survives Panama
restarts, and anything else on the system can change it, so a copy in
settings.json would drift -- the same reasoning as monitor brightness.

PerformanceDegraded is surfaced because it is what makes the setting a
lie: a thermally throttled machine reports "performance" while behaving
otherwise, and that is worth saying out loud.

The contract stubs busctl, because the real daemon is a system service
shared with everything else on the machine and a test that flipped the
daily driver to power-saver and then died would leave it there. It pins
the parsing in particular: busctl renders the Profiles property flat, so
profile names and driver names arrive in one stream, and a pattern loose
enough to match both reports the driver as an extra profile. On this
machine the driver is called "tuned", which reads exactly like a
plausible fourth profile -- verified the contract catches that, and
catches an unvalidated name reaching the system service.

Claude-Session: https://claude.ai/code/session_01BRvzt4H8XXLPVH5MyYdk9L

config/dot/quickshell/modules/settings/PowerPage.qml

@@ -14,9 +14,43 @@ import qs.services
 SettingsPage {
     id: root
 
+    // Probing the power daemon is a D-Bus round trip, so it happens when the
+    // page opens rather than at shell startup.
+    Component.onCompleted: if (!PowerProfiles.scanned) PowerProfiles.refresh()
+
     title: "Power & Lock"
     lede: "When the screen turns off, when the session locks, and whether it ever sleeps."
 
+    // The same profiles GNOME's Power panel offers. Not a stored preference --
+    // the daemon owns it, it survives Panama restarts, and anything else on the
+    // system can change it, so a copy here would drift.
+    SettingsCard {
+        visible: PowerProfiles.available || PowerProfiles.lastError !== ""
+        title: "Power profile"
+        subtitle: PowerProfiles.degraded !== ""
+            ? "Performance is limited right now: " + PowerProfiles.degraded
+            : (PowerProfiles.available
+                ? "Applies to the whole system and persists across sessions."
+                : PowerProfiles.lastError)
+
+        Repeater {
+            model: PowerProfiles.profiles
+
+            SettingRow {
+                id: profileRow
+                required property var modelData
+                required property int index
+
+                label: PowerProfiles.label(profileRow.modelData)
+                detail: PowerProfiles.detail(profileRow.modelData)
+                value: profileRow.modelData === PowerProfiles.active ? "Active" : ""
+                divider: profileRow.index < PowerProfiles.profiles.length - 1
+                activatable: profileRow.modelData !== PowerProfiles.active && !PowerProfiles.busy
+                onActivated: PowerProfiles.set(profileRow.modelData)
+            }
+        }
+    }
+
     SettingsCard {
         title: "Idle behaviour"
         subtitle: IdleLock.managed