Boost global text contrast and enlarge fonts slightly

Mirror the logrs treatment: at startup, pull every widget state's
foreground stroke toward white (dark) / black (light) so all UI text —
menus, top bar, buttons, panels, headings, not just the file list and
editor — reads more clearly against the theme background. Also scale
every base font size up ~12%. Explicitly coloured spans and the existing
per-pane contrast controls are unaffected and still layer on top.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app.rs

@@ -68,7 +68,8 @@ pub struct App {
 }
 
 impl App {
-    pub fn new(_cc: &eframe::CreationContext<'_>) -> Self {
+    pub fn new(cc: &eframe::CreationContext<'_>) -> Self {
+        apply_global_style(&cc.egui_ctx);
         let config = Config::load();
         let mut app = App {
             workspace_input: config.workspace.display().to_string(),
@@ -1489,6 +1490,45 @@ fn build_editor_job(
     job
 }
 
+/// Fraction each base font size is enlarged, applied once at startup so every
+/// panel's text is slightly bigger without changing layout maths elsewhere.
+const FONT_SCALE: f32 = 1.12;
+
+/// Configure the shared context style once at startup: raise the contrast of
+/// *all* UI text (menus, top bar, buttons, panels, headings — everything, not
+/// just the file list and editor) and enlarge every base font size slightly.
+///
+/// The default dark theme uses fairly dim greys (~140) for body text, the main
+/// legibility complaint; we pull each widget state's foreground toward white in
+/// dark mode / black in light mode. Explicitly coloured spans (grammar
+/// underlines, the cheatsheet's syntax colour) set their own colours and are
+/// unaffected. The per-pane boosts (`boost_list_contrast`, the editor contrast
+/// slider) still layer on top for their specific widgets.
+fn apply_global_style(ctx: &egui::Context) {
+    let mut style = (*ctx.style()).clone();
+
+    // Enlarge every text style (Body, Button, Heading, Monospace, Small).
+    for font in style.text_styles.values_mut() {
+        font.size = (font.size * FONT_SCALE).round();
+    }
+
+    let v = &mut style.visuals;
+    let target = if v.dark_mode {
+        egui::Color32::WHITE
+    } else {
+        egui::Color32::BLACK
+    };
+    let w = &mut v.widgets;
+    w.noninteractive.fg_stroke.color =
+        lerp_color(w.noninteractive.fg_stroke.color, target, 0.55);
+    w.inactive.fg_stroke.color = lerp_color(w.inactive.fg_stroke.color, target, 0.45);
+    w.hovered.fg_stroke.color = lerp_color(w.hovered.fg_stroke.color, target, 0.35);
+    w.active.fg_stroke.color = lerp_color(w.active.fg_stroke.color, target, 0.35);
+    w.open.fg_stroke.color = lerp_color(w.open.fg_stroke.color, target, 0.45);
+
+    ctx.set_style(style);
+}
+
 /// Raise the text contrast of list-style widgets in the current `ui`, so file
 /// names in the left pane stay legible against the panel background. Only the
 /// widget foreground colours are touched; layout and the rest of the app are