Resolve PDF export assets relative to posts

scripts/export-pdf.mjs

@@ -37,10 +37,14 @@ const outputPath = path.resolve(
 );
 mkdirSync(path.dirname(outputPath), { recursive: true });
 
+const resourcePath = [path.dirname(inputPath), repoRoot].join(path.delimiter);
+
 const pandocArgs = [
   inputPath,
   "--from",
   "markdown+fenced_code_attributes+tex_math_dollars+tex_math_single_backslash+footnotes+raw_html",
+  "--resource-path",
+  resourcePath,
   "--pdf-engine=lualatex",
   "--lua-filter",
   filterPath,