feat(ui): in-app FAQ, DPI-scaling audit fixes, mining/stratum polish + localize strings

Bundles the session's UI work (the touched files carry several of these
changes together, so they are committed as one coherent UI batch):

- FAQ: new RenderFaqDialog + data-driven faq_content, opened from a
  status-bar "?" (and the Windows title bar), styled like the Wallets
  modal with search, Wallet/Daemon tabs, and smooth scroll.
- DPI/font-scale audit: multiply hand-drawn absolute geometry by
  Layout::dpiScale() across ~30 files so nothing renders native-size at
  HiDPI / font_scale 1.5 (verified with a full sweep at 1.5x).
- Mining: chart now fills the horizontal space; thread stepper +/- buttons
  match the input-box height; move the stratum-host toggle into
  Node & Security (v1.3.0+).
- Settings: fix the auto-shield status text overlapping the grid.
- Sidebar: drop the peer-count badge on the Network button.
- i18n: wrap 193 hardcoded literals with TR() (keys/translations added in
  the preceding i18n commit), so the security/PIN/lock flow, seed-backup
  wizard, and witness-rebuild dialog localize.

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

CMakeLists.txt

@@ -521,6 +521,8 @@ set(APP_SOURCES
     src/ui/windows/settings_window.cpp
     src/ui/pages/settings_page.cpp
     src/ui/windows/about_dialog.cpp
+    src/ui/windows/faq_dialog.cpp
+    src/ui/windows/faq_content.cpp
     src/ui/windows/key_export_dialog.cpp
     src/ui/windows/transaction_details_dialog.cpp
     src/ui/windows/qr_popup_dialog.cpp
@@ -657,6 +659,8 @@ set(APP_HEADERS
     src/ui/windows/console_tab_helpers.h
     src/ui/windows/settings_window.h
     src/ui/windows/about_dialog.h
+    src/ui/windows/faq_dialog.h
+    src/ui/windows/faq_content.h
     src/ui/windows/key_export_dialog.h
     src/ui/windows/transaction_details_dialog.h
     src/ui/windows/qr_popup_dialog.h