feat(cronjobs): add shared HTTP client wrapper. Refs #1214

[Prasad8830]

Description

This PR introduces a shared HTTP client wrapper (HttpClient) based on requests.Session for our cronjob fetchers. This represents the first step towards standardising how cron jobs handle timeouts, retries, and errors, as discussed in #1214.

The wrapper automatically applies a default 10-second timeout, implements an exponential backoff retry strategy for standard server errors/rate limits, and consistently enforces raise_for_status(). Full unit tests for this wrapper have been included.

Note: This PR only introduces the wrapper and its tests. Subsequent PRs will migrate tor_exit_nodes, whatsmyip, and the remaining endpoints to use this new client.

Related issues

• Refs Standardize cronjob HTTP fetchers with a shared client wrapper #1214

Type of change

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Chore (refactoring, dependency updates, CI/CD changes, code cleanup, docs-only changes).

Checklist

Formalities

• I have read and understood the rules about how to Contribute to this project.
• I chose an appropriate title for the pull request in the form: <feature name>. Closes #999
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Docs and tests

• I documented my code changes with docstrings and/or comments.
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• I have added tests for the feature/bug I solved.
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GUI changes

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[regulartim]

Hey @Prasad8830 ! Nice work overall! :) A few things though:

• The issue was also about standardized logging but I can see no logging here. Please add a sensible amount of logging and also be thoughtful with the log levels.
• The retry behavior is not actually tested. Please add some tests for that, especially for the POST + retry case.

[Prasad8830]

Hey @Prasad8830 ! Nice work overall! :) A few things though:

• The issue was also about standardized logging but I can see no logging here. Please add a sensible amount of logging and also be thoughtful with the log levels.
• The retry behavior is not actually tested. Please add some tests for that, especially for the POST + retry case.

Thank you for bringing that to my attention! I will make the necessary corrections.