Added dpp spatial extent

[minhajuddin2510]

No description provided.

[jqnatividad]

Thanks @minhajuddin2510 for this work. Before this can land, a few concerns I'd like to flag for a follow-up version:

Scope. The PR title says "Added dpp spatial extent" but it also touches ai_suggestions.py, AI-suggestion JS / templates / web assets, jinja2 helpers, and plugin.py — looks like multiple unrelated features bundled together (~1900 lines across 12 files). Could you split this into smaller focused PRs? A reviewer can give a much better review on one feature at a time, and a regression in one feature won't block the others.

Description. The PR body is empty. For changes this size, a description covering (a) what each feature does, (b) why it's needed, (c) any operator-facing config / migration steps, (d) how it was tested would unblock review substantially.

Rebase needed. The PR targets the pre-migration codebase — it modifies ckanext/datapusher_plus/jobs.py, which the Prefect 3 migration (#277) deleted in favour of ckanext/datapusher_plus/jobs/stages/*.py. The current call sites are different too.

I'd suggest closing this and reopening one PR per feature (spatial extent / AI suggestions / etc.) on top of current main with descriptions. Happy to review each as it comes in.