refactor: rename file asset MCP service

Rename the Streamable HTTP MCP server and generated client config key from obsidian-wiki to wiki-file-assets so remote agents see the narrower file lookup purpose.

Keep existing tool names unchanged and cover the service name in tests.

scripts/manage_mcp_service.py

@@ -24,6 +24,7 @@ from obsidian_wiki.config import resolve_vault_path
 
 SERVICE_NAME = "obsidian-wiki-mcp.service"
 ENV_RELATIVE_PATH = Path(".runtime") / "obsidian-wiki-mcp.env"
+MCP_CLIENT_NAME = "wiki-file-assets"
 DEFAULT_HOST = "0.0.0.0"
 DEFAULT_PORT = 8765
 DEFAULT_PATH = "/mcp"
@@ -264,7 +265,7 @@ def render_remote_config(
         "Example MCP client config:\n"
         "{\n"
         '  "mcpServers": {\n'
-        '    "obsidian-wiki": {\n'
+        f'    "{MCP_CLIENT_NAME}": {{\n'
         '      "type": "streamable-http",\n'
         f'      "url": "{url}",\n'
         '      "headers": {\n'