feat(sound): per-app volume on the drawer page, output to 150%

The island spec put per-app volume on the drawer page, and it was never
built. Each application playing audio now gets a row with its name, what it
is playing (two browser tabs are otherwise identical rows), a click-to-mute
level and its own slider.

Streams are matched on PwNodeType.AudioOutStream. Quickshell reports isSink
true for a playback stream, so the obvious isStream && !isSink filter found
nothing while Firefox played. Their properties are empty until bound, so the
page carries a PwObjectTracker for them, which stops with the drawer.
speech-dispatcher-dummy is always present and never audible, and is hidden.

The output slider runs to 150%, the ceiling the volume keybind already uses
(wpctl -l 1.5), with a tick at 100%. Input and apps stop at 100%: a boosted
microphone only clips. The meter became an inline component shared by both,
and wheel-up never lowers a level already past its maximum.

Now playing is dropped from the page: the OSD already carries it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/desktop/modules/sound/README.md b/desktop/modules/sound/README.md
index 5205be8..365be4a 100644
--- a/desktop/modules/sound/README.md
+++ b/desktop/modules/sound/README.md
@@ -33,6 +33,22 @@ From Hyprland, to start the shell with the session:
 
     exec-once = qs -p ~/Programming/GIT/quickshell/desktop
 
+## The page
+
+Output and input, each with its device, a device picker and a slider, then
+one row per application playing audio, with its own slider and mute. The
+output slider runs to 150%, the ceiling the volume keybind uses
+(`wpctl -l 1.5`), with a tick at 100%; input and applications stop at 100%.
+Now playing is the OSD's job, not the page's.
+
+Applications are matched on `PwNodeType.AudioOutStream`, not on `isSink`:
+Quickshell reports `isSink` true for a playback stream, so the obvious
+`isStream && !isSink` filter returned nothing while Firefox was playing. A
+stream's `properties` (`application.name`, `media.name`) are empty until
+something binds the node, so the page carries its own `PwObjectTracker` for
+the streams. `speech-dispatcher-dummy` is a playback stream that is always
+present and never audible, and is filtered out by name.
+
 ## Now playing
 
 When an MPRIS player is running, a track row sits above the volume bar: album