feat(console): persist accent toggle + add monochrome-text toggle

Persist the two console output display preferences and add a second toolbar
toggle for monochrome text.

- Persistence: new Settings fields console_line_accents / console_text_color
  (both default true, matching the ConsoleTab statics so an upgrade re-save
  can't flip visible behavior). Restored into the statics at startup in the App
  constructor, and saved from a diff-and-save after the console renders (only
  when a value actually changed — save() is disk I/O). The startup restore also
  fixes a pre-existing bug: scanline was only synced from settings when the
  Settings page or first-run wizard ran, so an existing wallet ignored a saved
  scanline preference on launch.
- Monochrome text: a new toolbar toggle (FORMAT_COLOR_TEXT, dimmed when off)
  next to the accent toggle. channelTextColor() early-returns the neutral
  COLOR_RESULT for every channel (and JSON syntax role) when off, leaving the
  left accent bars independent. COLOR_RESULT is contrast-floored per theme, so
  text stays readable on light and dark terminals.

Adds console_toggle_text_color to the English source + all 8 translations.
Verified: both toggles independent, persistence round-trips across restart,
monochrome readable on light + dark skins.

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

src/config/settings.cpp

@@ -175,6 +175,8 @@ bool Settings::load(const std::string& path)
         loadScalar(j, "portfolio_style", portfolio_style_);
         if (portfolio_style_ < 0 || portfolio_style_ > 2) portfolio_style_ = 0;
         loadScalar(j, "scanline_enabled", scanline_enabled_);
+        loadScalar(j, "console_line_accents", console_line_accents_);
+        loadScalar(j, "console_text_color", console_text_color_);
         if (j.contains("hidden_addresses") && j["hidden_addresses"].is_array()) {
             hidden_addresses_.clear();
             for (const auto& a : j["hidden_addresses"])
@@ -425,6 +427,8 @@ bool Settings::save(const std::string& path)
     j["balance_layout"] = balance_layout_;  // saved as string ID
     j["portfolio_style"] = portfolio_style_;
     j["scanline_enabled"] = scanline_enabled_;
+    j["console_line_accents"] = console_line_accents_;
+    j["console_text_color"] = console_text_color_;
     j["hidden_addresses"] = json::array();
     for (const auto& addr : hidden_addresses_)
         j["hidden_addresses"].push_back(addr);