fix(theme): uniform contained-button text — white in light, black in dark

success/info/warning/error palettes had no explicit contrastText, so MUI auto-picked per color: in dark mode the brighter green/amber got black text while red/blue got white (inconsistent). Set contrastText explicitly per scheme (#fff in light, #1a1a1a in dark) so all contained color buttons (and filled chips) read uniformly — white on light, dark on dark.

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

src/admin/theme.ts

@@ -16,10 +16,10 @@ export const theme = createTheme({
       palette: {
         mode: "light",
         primary: { main: "#c73030" },
-        success: { main: "#15803d" },
-        warning: { main: "#b45309" },
-        error: { main: "#b91c1c" },
-        info: { main: "#1d4ed8" },
+        success: { main: "#15803d", contrastText: "#fff" },
+        warning: { main: "#b45309", contrastText: "#fff" },
+        error: { main: "#b91c1c", contrastText: "#fff" },
+        info: { main: "#1d4ed8", contrastText: "#fff" },
         background: { default: "#f4f3f1", paper: "#ffffff" },
         text: { primary: "#1a1a1a", secondary: "#555555" },
         divider: "rgba(0,0,0,0.1)",
@@ -29,10 +29,10 @@ export const theme = createTheme({
       palette: {
         mode: "dark",
         primary: { main: "#d63031" },
-        success: { main: "#22c55e" },
-        warning: { main: "#f59e0b" },
-        error: { main: "#ef4444" },
-        info: { main: "#3b82f6" },
+        success: { main: "#22c55e", contrastText: "#1a1a1a" },
+        warning: { main: "#f59e0b", contrastText: "#1a1a1a" },
+        error: { main: "#ef4444", contrastText: "#1a1a1a" },
+        info: { main: "#3b82f6", contrastText: "#1a1a1a" },
         background: { default: "#0f0f0f", paper: "#1a1a1a" },
         text: { primary: "#ffffff", secondary: "#a0a0a0" },
         divider: "rgba(255,255,255,0.08)",