fix: resolve 18 QA-discovered bugs across tools, previews, and the AI pipeline (#242)

Exhaustive QA sweep of all 157 tools. Fixes: CSP blob media, csv-excel ExcelJS interop, ocr-pdf segfault, chart-maker upload, non-PDF doc preview, RAW decode, merge-tool multi-file path, html-to-image chromium, ogv/wma/amr/ac3 preview fallbacks, meme/gif/stabilize codecs, nav+home a11y. Plus orphan-format and test-debt cleanup, the AI bundle build script, and a reusable Playwright QA harness under tests/qa/.

packages/ai/python/ocr_pdf.py

@@ -142,20 +142,19 @@ def main():
             elif was_auto:
                 current_lang = language  # already detected
 
-            # Run OCR engine based on quality tier
-            if quality == "fast":
-                text = ocr_module.run_tesseract(png_path, current_lang, is_auto=was_auto)
-                engine_used = "tesseract"
-            elif quality == "balanced":
-                text = ocr_module.run_paddleocr_v5(png_path, current_lang)
-                engine_used = "paddleocr-v5"
-            elif quality == "best":
-                text = ocr_module.run_paddleocr_vl(png_path)
-                engine_used = "paddleocr-vl"
-            else:
+            # Always route PDF OCR through tesseract.  PaddleOCR segfaults
+            # on arm64 CPU when processing rasterised PDF pages (SIGSEGV in
+            # the doc-orientation / structural-analysis stage).  Tesseract is
+            # reliable for page-level images and is already installed in the
+            # container with multi-language packs.  The image-OCR tool still
+            # offers PaddleOCR tiers for single images where it is stable.
+            if quality not in ("fast", "balanced", "best"):
                 print(json.dumps({"error": f"Unknown quality: {quality}"}))
                 sys.exit(1)
 
+            text = ocr_module.run_tesseract(png_path, current_lang, is_auto=was_auto)
+            engine_used = "tesseract"
+
             page_texts.append((page_num, text))
 
             # Clean up scratch PNG immediately