chore: add diagnostic logging for manifest mount resolution

- Log REPO_PATH, SSH_PATH, EXTRA_VOLUMES, manifest mounts, and resolved
  volumes in compile_compose() to trace why mounts may be missing
- Log repo_path and generated compose content in _prepare_manifest_instance()
  to verify the full compose YAML at start time

apps/api/src/api/tool_instances.py

@@ -1430,6 +1430,18 @@ async def _prepare_manifest_instance(
 
     compose_content = compile_compose(manifest, variables)
 
+    logger.debug(
+        "_prepare_manifest_instance for %s: repo_path=%s compose_volumes=%s",
+        instance.id,
+        repo_path or "<empty>",
+        manifest.get("mounts", []),
+    )
+    logger.debug(
+        "Generated compose for %s:\n%s",
+        instance.id,
+        compose_content,
+    )
+
     # Cache
     instance.image_tag = image_tag
     instance.manifest_compiled_at = datetime.now()