feat(parser): add OpenDataLoader, PaddleOCR-VL engines, and parser improvements

Introduce opendataloader and PaddleOCR-VL parser engines with tenant-level
settings UI, replace liteparse, and harden Excel/PPT/Markdown parsing.
Optional odl-hybrid sidecar stays local-build only and is excluded from
default dev-start and full profiles.

docreader/parser/markitdown_parser.py

@@ -9,6 +9,11 @@ from docreader.parser.base_parser import BaseParser
 from docreader.parser.chain_parser import PipelineParser
 from docreader.parser.concurrency import parser_worker_limit
 from docreader.parser.markdown_parser import MarkdownParser
+from docreader.parser.ppt_convert import normalize_ppt_bytes
+from docreader.parser.pptx_media import (
+    attach_pptx_media_to_markdown,
+    markdown_needs_pptx_media_attach,
+)
 
 logger = logging.getLogger(__name__)
 
@@ -32,16 +37,41 @@ class StdMarkitdownParser(BaseParser):
         Uses self.file_type (inherited from BaseParser) to hint the stream format.
         """
         ext = self.file_type
-        if ext and not ext.startswith('.'):
-            ext = '.' + ext
+        ft = (ext or "").lstrip(".").lower()
+        pptx_bytes: bytes | None = None
+        if ft in ("ppt", "pptx"):
+            content, ext = normalize_ppt_bytes(content, ft)
+            pptx_bytes = content
+            ft = "pptx"
+        elif ext and not ext.startswith("."):
+            ext = "." + ext
 
         with parser_worker_limit("markitdown", CONFIG.markitdown_max_workers):
-            result = self.markitdown.convert(
+            result = self._convert_markitdown(content, ext, keep_data_uris=True)
+            if result is None:
+                logger.warning(
+                    "MarkItDown failed with embedded images for %s; retrying without data URIs",
+                    ft or ext,
+                )
+                result = self._convert_markitdown(content, ext, keep_data_uris=False)
+
+        text = result.text_content
+        images: dict[str, str] = {}
+        if pptx_bytes is not None and markdown_needs_pptx_media_attach(text):
+            text, images = attach_pptx_media_to_markdown(text, pptx_bytes)
+        return Document(content=text, images=images)
+
+    def _convert_markitdown(self, content: bytes, ext: str | None, *, keep_data_uris: bool):
+        try:
+            return self.markitdown.convert(
                 io.BytesIO(content),
                 file_extension=ext,
-                keep_data_uris=True
+                keep_data_uris=keep_data_uris,
             )
-        return Document(content=result.text_content)
+        except Exception:
+            if keep_data_uris:
+                return None
+            raise
 
 
 class MarkitdownParser(PipelineParser):