fix(transport): add missing verify parameter to httpx.HTTPTransport

[IAOTW]

fix #16268

Summary

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

​​Affected Scope​​:

• External tool integration via Swagger API imports
• HTTPS client configuration in SSRF proxy module

​​Root Cause Analysis​​:

1. Global verify=False setting wasn't propagated to HTTPTransport initialization
2. SSL verification was hardcoded to True in transport layer (observed in error logs: CERTIFICATE_VERIFY_FAILED)16

​​Solution Implementation​​:

# Before
httpx.HTTPTransport(proxy=config.PROXY_URL)

# After 
httpx.HTTPTransport(
    proxy=config.PROXY_URL,
    verify=HTTP_REQUEST_NODE_SSL_VERIFY  # Added parameter
)

Screenshots

Before	After

Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods