feat(settings): adjustable opacity for the favorite gold outline + star

Adds a "Favorite Highlight Opacity" slider (15-100%, default 100%) to
Settings > Appearance > Scale & Effects. It scales the alpha of the four
favorite gold tokens (fill/border/icon/outline) at their resolve site in
the Balance address list via material::ScaleAlpha, so the gold row outline
and the star button fade together. The multiplier is skin-agnostic (it
scales whatever alpha the theme resolved) and touches only favorited rows;
non-favorite rows and the white selection highlight are unchanged, and the
100% default is byte-identical to the previous look.

The preference lives in Settings (favorite_opacity, clamped 0.15-1.0 in both
the setter and on load), persists across restarts, updates live, and is not
low-spec gated (it's a pure color-alpha preference, independent of the
transparency sliders). New i18n keys favorite_opacity / tt_favorite_opacity
are translated into all eight locales; the CJK subset font is rebuilt to add
the two new glyphs the zh string needs.

Verified: full + lite builds clean, full + lite test suites pass, hygiene OK.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/config/settings.h

@@ -261,6 +261,11 @@ public:
     float getNoiseOpacity() const { return noise_opacity_; }
     void setNoiseOpacity(float v) { noise_opacity_ = v; }
 
+    // Opacity multiplier for the favorite gold visuals (row outline + star button) in the
+    // Balance address list. 1.0 = theme default (unchanged); floor 0.15 so it can't vanish.
+    float getFavoriteOpacity() const { return favorite_opacity_; }
+    void setFavoriteOpacity(float v) { favorite_opacity_ = std::max(0.15f, std::min(1.0f, v)); }
+
     // Gradient background mode (use gradient variant of theme background)
     bool getGradientBackground() const { return gradient_background_; }
     void setGradientBackground(bool v) { gradient_background_ = v; }
@@ -685,6 +690,7 @@ private:
     int acrylic_quality_ = 2;
     float blur_multiplier_ = 0.10f;
     float noise_opacity_ = 0.5f;
+    float favorite_opacity_ = 1.0f;     // Favorite gold outline/star opacity multiplier (0.15–1.0, 1.0 = theme default)
     bool gradient_background_ = false;
 #ifdef _WIN32
     float ui_opacity_ = 0.50f;          // Card/sidebar opacity (0.3–1.0, 1.0 = opaque)