feat(mui): theme.ts with light/dark palettes, brand fonts, data-theme selector

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

src/admin/theme.ts

@@ -0,0 +1,56 @@
+import { createTheme } from "@mui/material/styles";
+
+const FONT_BODY = "'Plus Jakarta Sans', system-ui, sans-serif";
+const FONT_HEADING = "'Urbanist', sans-serif";
+const FONT_MONO = "'DM Mono', Menlo, monospace";
+
+export const theme = createTheme({
+  cssVariables: {
+    colorSchemeSelector: "[data-theme='%s']",
+  },
+  colorSchemes: {
+    light: {
+      palette: {
+        mode: "light",
+        primary: { main: "#c73030" },
+        success: { main: "#15803d" },
+        warning: { main: "#b45309" },
+        error: { main: "#b91c1c" },
+        info: { main: "#1d4ed8" },
+        background: { default: "#f4f3f1", paper: "#ffffff" },
+        text: { primary: "#1a1a1a", secondary: "#555555" },
+        divider: "rgba(0,0,0,0.1)",
+      },
+    },
+    dark: {
+      palette: {
+        mode: "dark",
+        primary: { main: "#d63031" },
+        success: { main: "#22c55e" },
+        warning: { main: "#f59e0b" },
+        error: { main: "#ef4444" },
+        info: { main: "#3b82f6" },
+        background: { default: "#0f0f0f", paper: "#1a1a1a" },
+        text: { primary: "#ffffff", secondary: "#a0a0a0" },
+        divider: "rgba(255,255,255,0.08)",
+      },
+    },
+  },
+  shape: { borderRadius: 10 },
+  typography: {
+    fontFamily: FONT_BODY,
+    h1: { fontFamily: FONT_HEADING, fontWeight: 800 },
+    h2: { fontFamily: FONT_HEADING, fontWeight: 800 },
+    h3: { fontFamily: FONT_HEADING, fontWeight: 800 },
+    h4: { fontFamily: FONT_HEADING, fontWeight: 700 },
+    h5: { fontFamily: FONT_HEADING, fontWeight: 700 },
+    h6: { fontFamily: FONT_HEADING, fontWeight: 700 },
+    button: { textTransform: "none", fontWeight: 600 },
+  },
+});
+
+export const fonts = {
+  body: FONT_BODY,
+  heading: FONT_HEADING,
+  mono: FONT_MONO,
+};