shell themes: give the launcher panel its own opacity

tokens.bg_alpha governs the bar, which stays readable at 0.72 because it
covers a thin strip of wallpaper. A full launcher panel at that alpha washes
out badly over a bright wallpaper and its text becomes hard to read — which
is what breadbox looked like, since it hardcoded 0.60 and read no theme value
at all.

Adds [launcher].panel_alpha, set to the approved reference's own values: 0.95
for glass-workbench, 0.93 for liquid-motion.

bread-theme/assets/shell/glass-workbench/theme.toml

@@ -121,6 +121,10 @@ search_font_size = 14
 search_padding_v = 12
 search_padding_h = 15
 # `.bx .r.sel { background: rgba(accent, .28) }`
+# Panel opacity, separate from tokens.bg_alpha (the bar). Matches the
+# approved reference: demo `.bx.gw{background:rgba(16,20,18,.95)}`. breadbox hardcoded 0.60, which washed the
+# panel out over a bright wallpaper.
+panel_alpha      = 0.95
 selection_alpha  = 0.28
 
 # Same four satellite namespaces as liquid-motion, keyed identically so the

bread-theme/assets/shell/liquid-motion/theme.toml

@@ -130,6 +130,10 @@ search_font_size = 16
 search_padding_v = 16
 search_padding_h = 18
 # `.bx .r.sel { background: rgba(accent, .22) }`
+# Panel opacity, separate from tokens.bg_alpha (the bar). Matches the
+# approved reference: demo `.bx.lm{background:rgba(21,14,23,.93)}`. breadbox hardcoded 0.60, which washed the
+# panel out over a bright wallpaper.
+panel_alpha      = 0.93
 selection_alpha  = 0.22
 
 # Keyed by layer-shell namespace, matching [compositor.*] below, so the two

bread-theme/src/shell/manifest.rs

@@ -202,6 +202,7 @@ pub(super) struct RawLauncher {
     pub(super) search_font_size: Option<i64>,
     pub(super) search_padding_v: Option<i64>,
     pub(super) search_padding_h: Option<i64>,
+    pub(super) panel_alpha: Option<f64>,
     pub(super) selection_alpha: Option<f64>,
 }
 
@@ -435,6 +436,9 @@ fn resolve_launcher(theme_id: &str, l: Option<&RawLauncher>) -> anyhow::Result<L
         search_font_size: l.and_then(|l| l.search_font_size).unwrap_or(16) as i32,
         search_padding_v: l.and_then(|l| l.search_padding_v).unwrap_or(12) as i32,
         search_padding_h: l.and_then(|l| l.search_padding_h).unwrap_or(16) as i32,
+        // 0.93 default, not breadbox's historical 0.60: a launcher panel needs
+        // near-opacity to stay legible over a bright wallpaper.
+        panel_alpha: l.and_then(|l| l.panel_alpha).unwrap_or(0.93),
         selection_alpha: l.and_then(|l| l.selection_alpha).unwrap_or(0.24),
     })
 }

bread-theme/src/shell/types.rs

@@ -256,6 +256,14 @@ pub struct Launcher {
     pub search_padding_v: i32,
     /// Search entry horizontal padding (px).
     pub search_padding_h: i32,
+    /// Opacity of the launcher PANEL itself, distinct from `tokens.bg_alpha`
+    /// (which governs the thin bar). A bar can be very translucent and stay
+    /// readable because it is 36-44px tall over a small slice of wallpaper; a
+    /// full launcher panel at the same alpha washes out badly over a bright
+    /// wallpaper and its text becomes hard to read. The approved reference
+    /// uses 0.95 (glass-workbench) and 0.93 (liquid-motion); breadbox
+    /// previously hardcoded 0.60, which is what made it look washed out.
+    pub panel_alpha: f64,
     /// Selected/hovered row background: `alpha(@accent, selection_alpha)`.
     /// Liquid Motion's softer 0.22 vs Glass Workbench's denser 0.28 — see
     /// each demo's `.bx .r.sel` rule.