feat(retry): add retry feature

[wantbook-book]

Issue resolved by this Pull Request:
Resolves #2465

Introduced a reusable retry-enabled HTTP helper (docling.utils.http_client) and refactored all existing remote requests calls to use it. This makes download helpers, HTML backend image fetches, and OpenAI-compatible image requests more resilient to transient errors and rate limiting without duplicating retry configuration.

Checklist:

• Documentation has been updated, if necessary.
• Examples have been added, if necessary.
• Tests have been added, if necessary.

[github-actions]

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[dosubot]

Related Documentation

Checked 5 published document(s) in 1 knowledge base(s). No updates required.

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[mergify]

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[wantbook-book]

❌ DCO Check Failed

Hi @wantbook-book, your pull request has failed the Developer Certificate of Origin (DCO) check.

This repository supports remediation commits, so you can fix this without rewriting history — but you must follow the required message format.

🛠 Quick Fix: Add a remediation commit

Run this command:

git commit --allow-empty -s -m "DCO Remediation Commit for akai <[email protected]>

I, akai <[email protected]>, hereby add my Signed-off-by to this commit: 51c66ae2cb98e3324e0edade364daae04af91d30
I, akai <[email protected]>, hereby add my Signed-off-by to this commit: 2144e015a59ea59def8db90ecb9cfd2c5b24ce64"
git push

🔧 Advanced: Sign off each commit directly
For the latest commit:

git commit --amend --signoff
git push --force-with-lease

For multiple commits:

git rebase --signoff origin/main
git push --force-with-lease

More info: DCO check report