Fix auth error handling

[hyongtao-code]

Fixes #24337

Unauthorized is a subclass of HTTPException -> Exception, so the old code silently swallowed it, causing 401 responses to never reach the client.

Now,

• Replace except Exception: pass with explicit handling:
• except Unauthorized: raise → let 401 bubble up correctly
• except Exception: → log and re-raise unexpected errors

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Summary

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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 dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[asukaminato0721]

how about #24427 :P