fix: use repository name for workspace mount target

WORKSPACE_NAME was computed from os.path.basename(repo_path), so when a
workspace path ended in a directory like 'main', the container mount target
became /home/user/main instead of /home/user/{repo-name}.

- Use GitRepository.name for WORKSPACE_NAME/REPO_NAME in manifest and
  legacy dockerfile flows
- Add unit test verifying prepare_manifest_instance uses repo.name even
  when the workspace path basename differs

Quality gates:
- pytest tests/unit: 213 passed
- ruff: clean on changed files
- mypy: clean on changed files

apps/api/src/services/tool/instance_service.py

@@ -887,7 +887,10 @@ async def prepare_manifest_instance(
             # The actual resolution happens in resolve_git_mounts; we store placeholder
             git_mount_vars[f"GIT_MOUNT_{ref}"] = ""
 
-    repo_name = os.path.basename(os.path.normpath(repo_path))
+    # Use the repository name for the workspace/repo mount target, not the
+    # directory name of a workspace/clone path (which may be "main" or similar).
+    repo = await session.get(GitRepository, instance.repository_id)
+    repo_name = repo.name if repo else os.path.basename(os.path.normpath(repo_path))
     variables = {
         "IMAGE_TAG": image_tag,
         "INSTANCE_NAME": instance.name.lower(),
@@ -1049,8 +1052,7 @@ async def create_tool_instance(
         )
 
         home_dir = tool_type.home_directory or "/home/user"
-        repo_name = os.path.basename(os.path.normpath(repo_path))
-        workspace_target = f"{home_dir}/{repo_name}"
+        workspace_target = f"{home_dir}/{repo.name}"
 
         compose_content = f"""version: "3.8"\nservices:
   app:
@@ -1086,15 +1088,14 @@ async def create_tool_instance(
 
         # Manifest templates use WORKSPACE_PATH; REPO_PATH is retained as a
         # deprecated alias for backward compatibility with older templates.
-        repo_name = os.path.basename(os.path.normpath(repo_path))
         variables = {
             "IMAGE_TAG": image_tag,
             "INSTANCE_NAME": instance_name.lower(),
             "INSTANCE_DIR": instance_dir,
             "WORKSPACE_PATH": repo_path,
             "REPO_PATH": repo_path,
-            "REPO_NAME": repo_name,
-            "WORKSPACE_NAME": repo_name,
+            "REPO_NAME": repo.name,
+            "WORKSPACE_NAME": repo.name,
             "SSH_PATH": "",
             "TOOL_PORT": tool_port,
             "EXTRA_ENV": {},
@@ -1115,7 +1116,7 @@ async def create_tool_instance(
             "TOOL_PORT": tool_port,
             "USER_ID": str(user_id),
             "PROJECT_ID": str(project_id),
-            "WORKSPACE_NAME": os.path.basename(os.path.normpath(repo_path)),
+            "WORKSPACE_NAME": repo.name,
             "HOME_DIRECTORY": tool_type.home_directory or "/home/user",
         }
         compose_content = render_compose_template(tool_type.compose_template, variables)