fix: custom comfy-api-base works with subpath

[BennyKok]

Fix URL joining issue in API client causing incorrect endpoint paths

Problem

When using API endpoints with paths starting with /, the urljoin function was incorrectly treating them as absolute paths, causing the base URL path to be stripped out.

Example:

• Base URL: https://api.comfydeploy.com/api/comfy-org/
• Path: /proxy/stability/v2beta/stable-image/generate/ultra
• Before: https://api.comfydeploy.com/proxy/stability/v2beta/stable-image/generate/ultra ❌
• After: https://api.comfydeploy.com/api/comfy-org/proxy/stability/v2beta/stable-image/generate/ultra ✅

Root Cause

Python's urljoin() follows RFC 3986 standards where paths starting with / are treated as absolute paths, replacing the entire path portion of the base URL instead of appending to it.

Solution

Modified the ApiClient.request() method to strip leading slashes from paths before passing them to urljoin, ensuring all paths are treated as relative.

# Before
url = urljoin(self.base_url, path)

# After  
relative_path = path.lstrip('/')
url = urljoin(self.base_url, relative_path)

Impact

• ✅ Fixes API endpoint URL construction for paths starting with /
• ✅ Maintains backward compatibility with existing relative paths
• ✅ Preserves urljoin functionality for proper URL handling
• ✅ No breaking changes to existing API integrations

Files Changed

• comfy_api_nodes/apis/client.py

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