fix: fix plugin miss version and checksum

[fatelei]

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Summary

fix #36081

when call https://marketplace.dify.ai/api/v1/plugins/download?unique_identifier=langgenius/deepseek

it need unique_identifier it author/plugin:version@checksum format, but currently it miss version@checksum, so it will fail {"code":-1,"data":null,"msg":"plugin unique identifier is invalid"}

and call

2026-05-12 11:39:46,89 ERROR [base.py:242] 787f6b0685 Failed to request plugin daemon, status: 400, url: plugin/f067162a-a141-4128-9836-ee2ad3623e94/management/fetch/manifest
Traceback (most recent call last):
  File "/Users/fatelei/dify/dify/api/core/plugin/impl/base.py", line 240, in _request_with_plugin_daemon_response
    response.raise_for_status()
  File "/Users/fatelei/dify/dify/api/.venv/lib/python3.12/site-packages/httpx/_models.py", line 829, in raise_for_status
    raise HTTPStatusError(message, request=request, response=self)
httpx.HTTPStatusError: Client error '400 Bad Request' for url 'http://127.0.0.1:10000/plugin/f067162a-a141-4128-9836-ee2ad3623e94/management/fetch/manifest?plugin_unique_identifier=langgenius%2Fdeepseek'

latest_package_identifier is the right format

Screenshots

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Checklist

• 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 make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods