feat(md-deck): add vertical alignment options to layers

Expand align from l/c/r to a 3x3 grid with vertical prefixes:
tl/tc/tr/bl/bc/br. Vertical position renders via flex
justify-content; compact layers strings and YAML both parse the
new values, and the layer editor dropdown gains corner/edge
options.

src/components/md-deck/hooks/layer-parser.ts

@@ -4,15 +4,16 @@ import { CSV } from "../../utils/csv-loader";
 /**
  * 解析 layers 字符串
  * 格式：body:1,7-5,8 title:1,1-4,1f6.6sl
- * f[fontSize] 表示字体大小（可选），方向字母（可选），对齐字母 l/c/r（可选）
+ * f[fontSize] 表示字体大小（可选），方向字母（可选），
+ * 对齐字母（可选）：水平 l/c/r，可加垂直前缀 t/b 组成 tl/tr/bl/br
  */
 export function parseLayers(layersStr: string): Layer[] {
   if (!layersStr) return [];
 
   const layers: Layer[] = [];
-  // 匹配：prop:x1,y1-x2,y2[ffontSize][direction][align]
+  // 匹配：prop:x1,y1-x2,y2[ffontSize][direction][[t|b]align]
   const regex =
-    /([^: ]+):(\d+),(\d+)-(\d+),(\d+)(?:f([\d.]+))?([nsew])?([lcr])?/g;
+    /([^: ]+):(\d+),(\d+)-(\d+),(\d+)(?:f([\d.]+))?([nsew])?([tb])?([lcr])?/g;
   let match;
 
   while ((match = regex.exec(layersStr)) !== null) {
@@ -24,7 +25,7 @@ export function parseLayers(layersStr: string): Layer[] {
       y2: parseInt(match[5]),
       fontSize: match[6] ? parseFloat(match[6]) : undefined,
       orientation: match[7] as "n" | "s" | "e" | "w" | undefined,
-      align: match[8] as "l" | "c" | "r" | undefined,
+      align: [match[8], match[9]].filter(Boolean).join("") as Layer["align"],
     });
   }