Let a sound device be heard, and the Dock's icons be sized

Nine outputs named after their chipsets cannot be told apart by reading, so each
one gets a Test button that plays a short sample out of that device. Targeted by
node name rather than by making it the default first, because finding out which
is which should not move where everything else is playing.

That belongs in its own service rather than in AudioDevices. sound-page-contract
forbids Process, pactl and wpctl in the files that own device state, and it is
right to: shelling out there races the PipeWire service that owns those same
objects. Playback is a different thing -- pw-play opens its own stream and
mutates no device, so there is nothing to race -- but the rule's letter covered
it, and weakening a guard to fit a new case is how guards stop meaning anything.
SoundTest exists so AudioDevices stays native bindings only.

Worth recording next to the call: pw-play falls back to the default output for a
target it cannot find, rather than failing. A stale node name would play from
the wrong device and look exactly like a successful test, which is why the name
is taken straight from the live node.

The Dock's icon size was a constant in Theme. It goes through the preference
schema like everything else, so validation, search, the generated docs and the
write sweep all pick it up without being told about it separately -- and two
contracts duly failed until docs/settings.md and the per-page commands were
regenerated.

Dock position is deliberately not here. It is not a setting but a rework: the
dock is anchored bottom, and the reveal strip, tooltip placement, intellihide
and the qs-dock rule in hypr/rules.lua all assume that. Doing it properly means
changing compositor rules on a machine somebody uses daily, which is not
something to start as a side effect of adding a slider.

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

docs/settings.md

@@ -4,7 +4,7 @@
 Do not edit this file. Run `quickshell/scripts/panama-settings-docs`
 after changing the schema; a contract fails when this copy is stale.
 
-131 settings across 27 groups. 67 of them are applied to the compositor and confirmed by reading the value back.
+132 settings across 27 groups. 67 of them are applied to the compositor and confirmed by reading the value back.
 
 ## accessibility
 
@@ -66,6 +66,7 @@ Found on **Desktop & Dock**.
 | Setting | Default | What it does |
 |---|---|---|
 | **Automatically hide the Dock**<br>`dockAutohide` | true | Reveal it at the bottom edge when a workspace is occupied |
+| **Icon size**<br>`dockIconSize` | 48 px | How large the Dock's application icons are drawn. Range 32–80. |
 | **Reveal delay**<br>`dockRevealDelayMs` | 0 ms | Zero reveals the Dock the instant the pointer reaches the edge. Range 0–1000. |
 | **Hide delay**<br>`dockHideDelayMs` | 250 ms | Prevents flicker when crossing between icons. Range 0–2000. |
 | **Pinned applications**<br>`dockPinned` | [ | Applications that stay in the Dock whether or not they are running |