feat(md-deck): support structured data-config with template layers

Allow md-deck layers to render markdown templates via {{var}}
substitution instead of only CSV props. Add config.ts to normalize
a JSON data-config attribute (size, grid, shape, layers) emitted by
the yaml code-block tag, taking precedence over legacy string props.

src/components/md-deck/config.test.ts

@@ -0,0 +1,106 @@
+import { layersToConfigs, normalizeDeckConfig } from "./config";
+
+describe("layersToConfigs", () => {
+  test("parses compact string format (legacy)", () => {
+    const layers = layersToConfigs("title:1,1-5,1f8 body:1,5-8,8f3");
+    expect(layers).toHaveLength(2);
+    expect(layers[0]).toMatchObject({
+      prop: "title",
+      visible: true,
+      x1: 1,
+      y1: 1,
+      x2: 5,
+      y2: 1,
+      fontSize: 8,
+    });
+    expect(layers[1].prop).toBe("body");
+  });
+
+  test("parses structured list with prop layers", () => {
+    const layers = layersToConfigs([
+      { prop: "name", x1: 1, y1: 1, x2: 5, y2: 2, font: 12 },
+    ]);
+    expect(layers).toHaveLength(1);
+    expect(layers[0]).toMatchObject({
+      prop: "name",
+      template: undefined,
+      visible: true,
+      x1: 1,
+      y1: 1,
+      x2: 5,
+      y2: 2,
+      fontSize: 12,
+    });
+  });
+
+  test("parses structured list with template layers", () => {
+    const layers = layersToConfigs([
+      { template: "**{{name}}**", x1: 1, y1: 3, x2: 5, y2: 8, align: "l" },
+    ]);
+    expect(layers).toHaveLength(1);
+    expect(layers[0]).toMatchObject({
+      prop: undefined,
+      template: "**{{name}}**",
+      visible: true,
+      x1: 1,
+      y1: 3,
+      x2: 5,
+      y2: 8,
+      align: "l",
+    });
+  });
+
+  test("returns [] for absent/empty input", () => {
+    expect(layersToConfigs()).toEqual([]);
+    expect(layersToConfigs("")).toEqual([]);
+    expect(layersToConfigs([])).toEqual([]);
+  });
+});
+
+describe("normalizeDeckConfig", () => {
+  test("parses string dimensions", () => {
+    const cfg = normalizeDeckConfig({ size: "54x86", grid: "5x8" });
+    expect(cfg.sizeW).toBe(54);
+    expect(cfg.sizeH).toBe(86);
+    expect(cfg.gridW).toBe(5);
+    expect(cfg.gridH).toBe(8);
+  });
+
+  test("parses array dimensions", () => {
+    const cfg = normalizeDeckConfig({ size: [63, 88] });
+    expect(cfg.sizeW).toBe(63);
+    expect(cfg.sizeH).toBe(88);
+  });
+
+  test("coerces numeric strings for bleed/padding", () => {
+    const cfg = normalizeDeckConfig({ bleed: "2", padding: "3" });
+    expect(cfg.bleed).toBe(2);
+    expect(cfg.padding).toBe(3);
+  });
+
+  test("normalizes layers and back_layers", () => {
+    const cfg = normalizeDeckConfig({
+      layers: [
+        { prop: "name", x1: 1, y1: 1, x2: 5, y2: 1 },
+        { template: "{{body}}", x1: 1, y1: 2, x2: 5, y2: 8 },
+      ],
+      back_layers: "logo:1,1-2,2",
+    });
+    expect(cfg.frontLayers).toHaveLength(2);
+    expect(cfg.frontLayers[1].template).toBe("{{body}}");
+    expect(cfg.backLayers).toHaveLength(1);
+    expect(cfg.backLayers[0].prop).toBe("logo");
+  });
+
+  test("missing fields stay undefined", () => {
+    const cfg = normalizeDeckConfig({});
+    expect(cfg.sizeW).toBeUndefined();
+    expect(cfg.sizeH).toBeUndefined();
+    expect(cfg.gridW).toBeUndefined();
+    expect(cfg.gridH).toBeUndefined();
+    expect(cfg.bleed).toBeUndefined();
+    expect(cfg.padding).toBeUndefined();
+    expect(cfg.frontLayers).toEqual([]);
+    expect(cfg.backLayers).toEqual([]);
+  });
+});