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>

src/ui/windows/chat_tab.cpp

@@ -425,9 +425,9 @@ void RenderChatSettingsPreview(App* app, float width) {
     struct PMsg { const char* body; bool outgoing; bool startGroup; bool lastInGroup; std::string meta; };
     const std::string peer = "Ava";
     const PMsg msgs[] = {
-        { u8"Did the payment go through? \U0001F642", false, true,  true,  peer + "  " + t1 },
-        { u8"Yep — just confirmed ✅",       true,  true,  false, std::string(TR("chat_you")) + "  " + t2 },
-        { u8"Sending the rest now \U0001F44D",         true,  false, true,  std::string() },
+        { TR("grpb_preview_msg_payment_through"), false, true,  true,  peer + "  " + t1 },
+        { TR("grpb_preview_msg_yep_confirmed"),       true,  true,  false, std::string(TR("chat_you")) + "  " + t2 },
+        { TR("grpb_preview_msg_sending_rest"),         true,  false, true,  std::string() },
     };
     const int N = 3;