feat(upload): accept legacy .doc, convert via LibreOffice in container

Legacy Hebrew .doc precedents (e.g. nevo.co.il CP1255 OLE2) can now be
uploaded directly through the precedent-library, missing-precedent, and
training upload paths — the frontend already advertised .doc but the
backend gate rejected it before reaching the extractor.

- web/app.py: add .doc to ALLOWED_EXTENSIONS (covers all paths that share
  the set: precedent library, missing-precedent, training).
- Dockerfile: install libreoffice-writer-nogui (no X11/Java) so the
  extractor's existing _extract_doc LibreOffice conversion works in the
  Coolify container (was missing → would fail at runtime).
- extractor.py: isolate the LibreOffice user profile per call to avoid a
  profile-lock failure on concurrent .doc conversions.

Verified in python:3.12-slim (prod base): .doc→.docx→text yields text
byte-identical to a native Word .docx save (103 paragraphs, 24,341 chars).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mcp-server/src/legal_mcp/services/extractor.py

@@ -262,8 +262,15 @@ def _ocr_with_google_vision(image_bytes: bytes, page_num: int) -> str:
 def _extract_doc(path: Path) -> str:
     """Extract text from legacy .doc file by converting to .docx via LibreOffice."""
     with tempfile.TemporaryDirectory() as tmp_dir:
+        # Isolate the LibreOffice user profile per call: headless soffice
+        # locks a single shared profile, so concurrent .doc conversions would
+        # otherwise fail with a profile-lock error.
         result = subprocess.run(
-            ["libreoffice", "--headless", "--convert-to", "docx", str(path), "--outdir", tmp_dir],
+            [
+                "libreoffice",
+                f"-env:UserInstallation=file://{tmp_dir}/lo-profile",
+                "--headless", "--convert-to", "docx", str(path), "--outdir", tmp_dir,
+            ],
             capture_output=True, text=True, timeout=120,
         )
         if result.returncode != 0: