feat(debug): theme x tab screenshot sweep + Debug options dialog

Add a debug tool that cycles every skin across every build-enabled tab and saves a
PNG of each to a timestamped folder under the config dir (screenshots/sweep_<ts>/)
— for gathering visual context on theme-specific UI work.

- App state machine (app_network.cpp): startScreenshotSweep() builds the
  skin+enabled-page lists, saves the current skin/page, and steps through them;
  updateScreenshotSweep() (top of App::render) pins the page + settles ~4 frames
  after each skin/page change (skin switches reload TOML + reset the acrylic
  capture, so they need to settle); wantsScreenshotThisFrame()/screenshotSweepPath()
  /onScreenshotCaptured() coordinate with main.cpp. Restores the original skin/page
  when done; nothing persisted.
- Framebuffer capture (main.cpp): read the finished frame and encode PNG via the
  bundled miniz (tdefl_write_image_to_png_file_in_memory_ex). GL reads FBO 0 (RGBA,
  bottom-up -> flip); DX11 copies the backbuffer to a staging texture + maps it
  (BGRA, top-down -> channel-swap). Alpha forced opaque.
- Settings UI: move the Verbose logging checkbox off the wallet row into a new
  "Debug options" button that opens a dialog housing the verbose toggle + a "Run
  screenshot sweep" button. New i18n keys.

Both platforms build; no-crash smoke verified.

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

src/app.cpp

@@ -1243,6 +1243,10 @@ void App::render()
     // Process deferred encryption from wizard (runs in background)
     processDeferredEncryption();
 
+    // Debug screenshot sweep — pins the current (skin,page) and arms capture once settled. Must run
+    // before the sidebar reads current_page_ (below) so the forced page is reflected.
+    updateScreenshotSweep();
+
     // While any full-window BLUR overlay is open: (1) suppress panel theme-effects for the whole
     // frame so their foreground-draw-list borders (sidebar included) don't bleed over the overlay;
     // (2) mark a full-window blur overlay active so glass panels use their opaque fallback (they're