fix: use relative paths for SVG imports to pass Vite fs.allow during build

Slidev converts <img src> to ES imports during build. Absolute paths like
/pipeline.svg resolve to the filesystem root, failing the slidev:slide-import-guard
plugin. Changed to relative ../public/ paths so imports resolve within the project.

decks/gen2D/pages/data-model.md

@@ -3,7 +3,7 @@
 四表结构，清晰的实体关系
 
 <div class="flex justify-center">
-  <img src="/data-model.svg" class="w-full max-h-[250px] object-contain" />
+  <img src="../public/data-model.svg" class="w-full max-h-[250px] object-contain" />
 </div>
 
 <div class="grid grid-cols-2 gap-4 mt-2">