feat(ui): settings polish — button retune, daemon card, RPC 2-row, chat preview

Settings tabs brought closer to the approved mockup:
- ActionButton/renderCardButton retune (settings-scoped): 7px radius, 9px
  padX, Primary → accent-outline chip, Secondary/card buttons more defined.
- Daemon-binary card: compact status right-aligned on the DAEMON BINARY
  heading (Up to date / Version differs / Not installed), filled/rounded
  status box, neutral danger divider (was alarming red), roomier spacing.
- RPC Connection: two-row column-aligned layout (Host | Port, then
  Username | Password) so the password no longer clips off the card edge.
- Chat settings tab: live conversation preview below the Appearance /
  Messaging cards; "Focus input on open" checkbox reflowed onto the console
  color-toggle row.
- Debug Options: "Current theme only" toggle restricts either screenshot
  sweep to the active theme instead of cycling every skin.
- Tabs fill the full content width (content-max-width cap disabled) and the
  sidebar nav panel centers within the true visible area.
- i18n: new keys for the above (untranslated keys fall back to English).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app.h

@@ -408,6 +408,9 @@ public:
     // each under every skin. Output: <config>/screenshots-full/<surface>/<skin>.png + an index.
     void startFullUiSweep();
     std::string screenshotFullDir() const;
+    // Debug option: restrict either sweep to just the currently-active theme instead of cycling all.
+    bool sweepCurrentThemeOnly() const { return sweep_current_theme_only_; }
+    void setSweepCurrentThemeOnly(bool v) { sweep_current_theme_only_ = v; }
     bool isScreenshotSweeping() const { return screenshot_sweep_active_; }
     bool wantsScreenshotThisFrame() const { return sweep_capture_this_frame_; }
     const std::string& screenshotSweepPath() const { return sweep_current_path_; }
@@ -1114,6 +1117,7 @@ private:
 
     // Debug screenshot sweep state.
     bool  screenshot_sweep_active_    = false;
+    bool  sweep_current_theme_only_   = false;   // Debug Options: sweep only the active theme
     bool  sweep_capture_this_frame_   = false;
     int   sweep_skin_idx_             = 0;
     int   sweep_settle_frames_        = 0;   // frames to let a new skin/surface settle before capture