fix: remove duplicate /api/recommend route

[saurabhhhcodes]

Summary

Fixes #1649.

What changed

• Moved the orphaned paginated recommendations handler off GET /api/recommend and onto GET /api/recommend/paginated.
• Kept the canonical /api/recommend and /api/recommend/{item_title} handlers intact for the existing query/title flow.
• Fixed the query-title ordering in the main recommendation handler so cache keys are built after the request title is resolved.
• Added a regression test that asserts the route registry has exactly one GET /api/recommend handler and one paginated handler.

Validation

• python3 -m py_compile backend/main.py tests/test_recommend_api.py
• git diff --check

Notes

The local test runner still hits an environment dependency gap when importing the app (websockets.asyncio), so I used syntax and route-registry validation for this branch.

[github-actions]

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[github-actions]

⚠️ Main branch was just updated!

PR #1633 ("fix: Duplicate results-processing loop removed from search_items(#1631)") was just merged into main.

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⚠️ Main branch was just updated!

PR #1647 ("fix: add title query param endpoint to resolve HTTP 422 (#1075)") was just merged into main.

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⚠️ Main branch was just updated!

PR #1648 ("fix(federated): prevent regularization decay in aggregate_updates") was just merged into main.

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⚠️ Main branch was just updated!

PR #1650 ("fix: remove duplicate code block in hybrid_model.py causing Indentati…") was just merged into main.

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[leonagoel]

🎉 Merged!

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