Add pagination to admin source list pages (#103)

* Add pagination to admin source list pages

- Add pagination controls (Prev/Next) to all admin source list pages
- Show 20 sources per page with "Showing X-Y of Z sources" info
- Pagination appears at both top and bottom of long lists
- Controls only appear when there's more than one page
- Works for Active, Disabled, Needs Configuration, and Robots Blocked pages
- Uses HTMX for seamless page navigation without full page reload

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Co-Authored-By: Claude <noreply@anthropic.com>

* Fix pagination in mutation endpoints and template page size

Code review fixes:
- Create _get_paginated_sources() helper to share pagination logic
- Update mutation endpoints (delete, toggle, mark-disabled, recheck-robots,
  create) to return paginated results instead of unpaginated lists
- Replace hard-coded page size (20) in template with page_size variable
- Add page_size to all GET list endpoint responses

This ensures pagination controls persist after actions like delete/toggle,
and the template will automatically reflect any changes to SOURCES_PER_PAGE.

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Co-Authored-By: Claude <noreply@anthropic.com>

* Fix pagination edge cases and consolidate GET list endpoints

Address code review feedback on PR #103:
- Thread current page from HX-Current-URL header through mutation
  endpoints (delete, toggle, mark-disabled, recheck-robots) so users
  don't lose their place after actions
- Refactor all four GET list endpoints to use _get_paginated_sources
  helper, ensuring consistent page clamping to prevent invalid ranges
  like "Showing 21-10 of 10"

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Co-Authored-By: Claude <noreply@anthropic.com>

* Fix pagination: pass current page via hx-vals instead of HX-Current-URL

The HX-Current-URL header contains the browser URL (e.g., /admin) which
never has a page param since pagination doesn't push to browser URL.

Fix by:
- Adding hx-vals='{"page": "{{ page }}"}' to all mutation buttons
  (recheck-robots, delete, mark-disabled, toggle)
- Update _get_current_page_from_request to read from query params
  (DELETE) or form data (POST) where htmx sends hx-vals
- Make mutation endpoints async to await form parsing

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Co-Authored-By: Claude <noreply@anthropic.com>

* Docs: Add admin source list pagination to status

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Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: mbuckingham74

CLAUDE_STATUS.md

@@ -924,6 +924,23 @@ Default State: AK
 - **SitemapScraper:** Shows when `sitemap_url` is configured
 - **DynamicScraper:** Shows when `custom_scraper_code` exists
 
+### Admin Source List Pagination ✅
+- [x] Paginated source lists (20 per page) across all admin pages
+- [x] Pagination controls (Prev/Next) with page info ("Showing 1-20 of 45 sources")
+- [x] Page clamping to prevent invalid ranges (e.g., page 3 of 2 clamps to page 2)
+- [x] Mutation actions (Delete, Toggle, Mark Disabled, Recheck) preserve current page
+- [x] Consolidated `_get_paginated_sources` helper for consistent pagination logic
+
+**Key Files:**
+- `backend/app/routers/admin.py` - Pagination helper and endpoint updates
+- `backend/app/templates/admin/partials/source_list.html` - Pagination controls with `hx-vals`
+
+**Technical Details:**
+- `SOURCES_PER_PAGE = 20` constant for page size
+- `_get_paginated_sources()` returns paginated sources with context flags
+- `_get_current_page_from_request()` extracts page from htmx `hx-vals` (form data for POST, query params for DELETE)
+- All mutation buttons include `hx-vals='{"page": "{{ page }}"}'` to preserve position
+
 ## CSS Selector Troubleshooting
 
 Common issues when configuring GenericScraper: