fix: v0.5.1 — pull_image API (Image/pull_start, not Registry/pull_start)

The 0.5.0 prompt mis-attributed the API: pull_start lives on
SYNO.Docker.Image, not SYNO.Docker.Registry (live DSM capture).
search and tags ARE correctly on Registry; only pull_start belongs
to Image. Registry/pull_start returns "Method does not exist".

Parameters are unchanged (repository + tag both JSON-encoded), and
the Image/list polling for completion detection is untouched.

Tests updated to assert SYNO.Docker.Image/pull_start. CLAUDE.md
DSM-quirks section consolidates the Image vs. Registry split so
this trap is documented for future surface additions. References
#3 (already closed).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/mcp_synology_container/modules/registry.py

@@ -169,9 +169,13 @@ def register_registry(mcp: FastMCP, config: AppConfig, client: DsmClient) -> Non
         if await _image_present(client, repository, tag):
             return f"{target} is already present locally — nothing to pull."
 
+        # `pull_start` lives on SYNO.Docker.Image, NOT SYNO.Docker.Registry
+        # (live DSM capture, confirmed). The Registry API only exposes the
+        # synchronous read-only methods (search, tags, get/set/create/delete,
+        # using).  Calling Registry/pull_start returns "Method does not exist".
         try:
             await client.request(
-                "SYNO.Docker.Registry",
+                "SYNO.Docker.Image",
                 "pull_start",
                 version=1,
                 params={