feat(storage): X14 Phase 2c — route remaining sync write-sites through storage.py

Completes the write-side rewiring (INV-STG1) for the call-sites that run in
synchronous contexts, via a new blocking facade in storage.py
(put_bytes_sync / put_file_sync — asyncio.run, or a worker thread when a loop
is already running):
- services/extractor.py: multimodal thumbnail JPEGs → DERIVED (rendered in a
  to_thread worker)
- services/docx_reviser.py: track-changes save (_save_docx_xml) + empty-diff
  copy (copy_with_revisions) → DOCUMENTS
- services/docx_retrofit.py: in-place retrofit backup → DOCUMENTS

Each site keeps a fallback to a direct disk write when the target path is
outside DATA_DIR (caller-provided). Under the default STORAGE_BACKEND=
filesystem the bytes land exactly where they did before — zero behaviour
change.

Also: mcp_env_catalog MINIO_ENDPOINT default updated to the durable
container-name endpoint (http://minio-bx2ykvw94xbutsex41hz4vv8:9000), matching
the Coolify "Connect to Predefined Network" change made for network durability.

All binary write-sites now flow through storage.py. git-tracked text
(case.json/notes/research-md/draft-md) stays on disk by design (INV-STG7);
court-fetch temp files are ephemeral.

tests: +2 (thumbnail renderer routes through storage; put_bytes_sync
round-trip); 55 storage/docx/track-changes green; 244 collected, no import
breakage.

Keeps G2; completes INV-STG1 write coverage. Spec: docs/spec/X14-storage-minio.md.

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

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

@@ -23,6 +23,7 @@ from docx import Document as DocxDocument
 from striprtf.striprtf import rtf_to_text
 
 from legal_mcp import config
+from legal_mcp.services import storage
 
 if TYPE_CHECKING:
     from google.cloud import vision
@@ -345,7 +346,19 @@ def render_pages_for_multimodal(
                     max(1, int(img.height * ratio)),
                 )
                 thumb = img.resize(thumb_size, Image.Resampling.LANCZOS)
-                thumb.save(thumb_path, "JPEG", quality=75, optimize=True)
+                # Persist the thumbnail (a DERIVED, regenerable artifact)
+                # through the storage layer (INV-STG1). Under the filesystem
+                # backend it lands at thumb_path exactly as before.
+                _tbuf = io.BytesIO()
+                thumb.save(_tbuf, "JPEG", quality=75, optimize=True)
+                try:
+                    _tkey = thumb_path.resolve().relative_to(
+                        Path(config.DATA_DIR).resolve()).as_posix()
+                    storage.put_bytes_sync(
+                        _tkey, _tbuf.getvalue(), bucket=storage.Bucket.DERIVED,
+                        content_type="image/jpeg")
+                except ValueError:
+                    thumb.save(thumb_path, "JPEG", quality=75, optimize=True)
 
             out.append((img, thumb_path))
     finally: