feat(csv-loader): strip comments before parsing CSV

Pre-filter comment lines from the content before passing it to
`csv-parse`. This prevents quote parsing errors when comment lines
contain double quotes and simplifies the record filtering logic.

src/csv-loader/loader.ts

@@ -789,34 +789,41 @@ export function parseCsv(
   const refBaseDir = options.refBaseDir;
   const defaultPrimaryKey = options.defaultPrimaryKey ?? "id";
 
-  const records = parse(content, {
+  // Pre-strip comment lines from content before passing to csv-parse,
+  // to avoid quote parsing errors in comment lines containing double quotes.
+  const reverseReferences: ReverseReferenceDeclaration[] = [];
+  let filteredContent = content;
+  if (comment) {
+    const lines = content.split(/\r?\n/);
+    const nonCommentLines: string[] = [];
+    for (const line of lines) {
+      const trimmed = line.trim();
+      if (trimmed.startsWith(comment)) {
+        const decl = parseReverseReferenceDeclaration(trimmed, comment);
+        if (decl) {
+          reverseReferences.push(decl);
+        }
+        // Skip comment lines
+      } else {
+        nonCommentLines.push(line);
+      }
+    }
+    filteredContent = nonCommentLines.join("\n");
+  }
+
+  const records = parse(filteredContent, {
     delimiter,
     quote,
     escape,
     bom,
-    // Don't let csv-parse skip comments; we need to parse them for reverse references.
-    // Comment lines are filtered out manually below using the configured comment character.
     comment: undefined,
     trim,
     skip_empty_lines: true,
     relax_column_count: true,
   });
 
-  // Filter out comment lines from all records, collecting reverse reference declarations
-  const reverseReferences: ReverseReferenceDeclaration[] = [];
-  const filteredRecords: string[][] = [];
-  for (const row of records) {
-    const firstCell = (row[0] ?? "").trim();
-    if (comment && firstCell.startsWith(comment)) {
-      const decl = parseReverseReferenceDeclaration(firstCell, comment);
-      if (decl) {
-        reverseReferences.push(decl);
-      }
-      // Skip comment lines (whether or not they're reverse ref declarations)
-      continue;
-    }
-    filteredRecords.push(row);
-  }
+  // Comment lines were already filtered out before parsing
+  const filteredRecords = records;
 
   if (filteredRecords.length < 2) {
     throw new Error("CSV must have at least 2 rows: headers and schemas");