fix: v0.4.3 — inspect_image rendering polish (follow-up to #4)

Three live-NAS observations that the 0.4.2 implementation got wrong:

1. Header showed "?:?" — DSM Image/get returns image="" and tag=""
   for name:tag lookups; the response fields are unreliable. The
   header now echoes the user-supplied image_id, falling back to the
   sha256 id only when image_id itself is empty.

2. Ports printed as raw Python dicts ({'port':'22','protocol':'tcp'}).
   The ports array is a list of {port, protocol} objects — each entry
   now renders as "22/tcp".

3. Environment printed as raw Python dicts ({'key':'PATH','value':...}).
   The env array is a list of {key, value} objects — each entry now
   renders as "PATH=/usr/local/...".

cmd, entrypoint, and volumes (plain string arrays) were already
correct and are untouched. Tests updated to match the live shape;
two new tests guard the header fallback. References #4 (already
closed by 0.4.2 — no need to reopen for a rendering polish).

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

src/mcp_synology_container/modules/images.py

@@ -290,10 +290,12 @@ def register_images(mcp: FastMCP, config: AppConfig, client: DsmClient) -> None:
         if not isinstance(data, dict) or not data:
             return f"Image '{image_id}' not found."
 
-        repo = data.get("image") or "?"
-        tag = data.get("tag") or "?"
-        display_name = f"{repo}:{tag}"
         img_hash = data.get("id") or ""
+        # The DSM Image/get response leaves `image` and `tag` empty when the
+        # lookup is by name:tag (live-confirmed against the NAS), so the
+        # response fields are unreliable for the header. Prefer the user-
+        # supplied image_id, then fall back to the id hash.
+        display_name = image_id or img_hash or "?"
         digest = data.get("digest") or ""
         size_val = data.get("size") or 0
         virtual_size_val = data.get("virtual_size") or 0
@@ -301,9 +303,9 @@ def register_images(mcp: FastMCP, config: AppConfig, client: DsmClient) -> None:
         docker_version = data.get("docker_version") or ""
         cmd = data.get("cmd") or []
         entrypoint = data.get("entrypoint") or []
-        env_list: list[str] = data.get("env") or []
-        ports: list[str] = data.get("ports") or []
-        volumes: list[str] = data.get("volumes") or []
+        env_list: list[Any] = data.get("env") or []
+        ports: list[Any] = data.get("ports") or []
+        volumes: list[Any] = data.get("volumes") or []
 
         lines = [f"Image: {display_name}"]
         if img_hash:
@@ -337,7 +339,13 @@ def register_images(mcp: FastMCP, config: AppConfig, client: DsmClient) -> None:
             lines.append("")
             lines.append(f"Exposed ports ({len(ports)}):")
             for port in ports:
-                lines.append(f"  {port}")
+                # Live shape: {"port": "22", "protocol": "tcp"}.
+                if isinstance(port, dict):
+                    port_num = port.get("port", "?")
+                    proto = port.get("protocol", "tcp")
+                    lines.append(f"  {port_num}/{proto}")
+                else:
+                    lines.append(f"  {port}")
 
         if volumes:
             lines.append("")
@@ -349,7 +357,13 @@ def register_images(mcp: FastMCP, config: AppConfig, client: DsmClient) -> None:
             lines.append("")
             lines.append(f"Environment ({len(env_list)}):")
             for var in env_list:
-                lines.append(f"  {var}")
+                # Live shape: {"key": "PATH", "value": "/usr/local/sbin"}.
+                if isinstance(var, dict):
+                    key = var.get("key", "?")
+                    value = var.get("value", "")
+                    lines.append(f"  {key}={value}")
+                else:
+                    lines.append(f"  {var}")
 
         return "\n".join(lines)