Fix hidden and expired items in recommendation results

[eyupcanakman]

Fixes #764

Summary

Recommendation results could still include hidden items and items older than item_ttl.

Filter cached and fallback recommendation results against current item metadata, and keep scanning past filtered entries so valid items still fill the response. Keep cache-only IDs without item rows unchanged.

Testing

• go test ./logics ./server ./worker -count=1
• go test ./... -run '^$' -count=1

[codecov]

Codecov Report

❌ Patch coverage is 79.31034% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.74%. Comparing base (b507ecb) to head (6bcce5e).
⚠️ Report is 18 commits behind head on master.

Files with missing lines	Patch %	Lines
logics/recommend.go	79.31%	9 Missing and 9 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1192      +/-   ##
==========================================
+ Coverage   72.72%   72.74%   +0.01%     
==========================================
  Files          88       88              
  Lines       16258    16333      +75     
==========================================
+ Hits        11824    11881      +57     
- Misses       3233     3242       +9     
- Partials     1201     1210       +9     

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[eyupcanakman]

#1206 now pushes ItemTTL into the storage query and #1197 keeps hidden items out of the item-to-item index. The remaining paths (Recommend, Collaborative, NonPersonalized, UserToUser, External) still aren't filtered. Want me to rebase and narrow this to those, or close it and file smaller follow-ups that match your approach?

[zhenghaoz]

#1206 now pushes ItemTTL into the storage query and #1197 keeps hidden items out of the item-to-item index. The remaining paths (Recommend, Collaborative, NonPersonalized, UserToUser, External) still aren't filtered. Want me to rebase and narrow this to those, or close it and file smaller follow-ups that match your approach?

Thank you for your reply. New BatchGetItem could be used for filtering now. You could close this PR if rebase is more hard than open a new one.

[eyupcanakman]

Closing. I'll open a narrower follow-up using the new BatchGetItems options.