fix: suppress markdown when all pages have gid-encoded fonts

When every page uses fonts with unresolvable gid-encoded glyphs,
the extracted text is unreliable garbage. Suppress the markdown
output so consumers know to use OCR instead.

Only triggers for gid-encoded fonts specifically, not for other
OCR signals (Identity-H without ToUnicode, template images) where
the text layer may still be partially useful.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lib.rs

@@ -449,7 +449,9 @@ fn process_document(
         (markdown, has_encoding_issues, false)
     };
 
-    // Add pages with gid-encoded fonts (unresolvable encoding) to OCR list
+    // Add pages with gid-encoded fonts (unresolvable encoding) to OCR list.
+    // When ALL pages have gid-encoded fonts, suppress unreliable markdown.
+    let all_gid = !gid_pages.is_empty() && gid_pages.len() as u32 >= page_count;
     let mut pages_needing_ocr = pages_needing_ocr;
     if force_ocr_all {
         pages_needing_ocr = (1..=page_count).collect();
@@ -464,6 +466,16 @@ fn process_document(
         pages_needing_ocr.sort_unstable();
     }
 
+    let markdown = if all_gid {
+        log::debug!(
+            "all {} pages have gid-encoded fonts — suppressing markdown output",
+            page_count
+        );
+        None
+    } else {
+        markdown
+    };
+
     Ok(PdfProcessResult {
         pdf_type,
         markdown,