fix(search): advanced search now ORs same-column filters

[sreeshanth-soma]

Closes: #129

Summary

Fixes Advanced Search logic so multiple values for the same field are OR-grouped, while different fields remain AND-combined.

This makes queries behave as expected:

(genre = Action OR genre = ComedyFunny)
AND type = …
AND additional filters

Problem

search_filters_where_array() previously built a flat list of SQL conditions, and the caller joined everything with AND.

So selecting two genres produced:
genre_id = "1" AND genre_id = "2"

which can never match a single row, causing zero results.

Changes

Backend — core/models/media_model.php

• Updated search_filters_where_array() to:
  • Build each filter SQL condition as before.
  • Group conditions by resolved SQL column name (after metadata/alias resolution)
  • OR conditions inside each same-column group.
  • Return grouped clauses for existing outer AND join behavior.
• Kept all existing operator/default handling intact (eq, contains, has, metadata defaults, etc.).
• Hoisted metadata/column mapping setup outside the per-filter loop for better efficiency.

Verification Steps

• Open Sidebar → Media → Advanced Search.
• Add filter: Genre is Action, click Add.
• Add filter: Genre is ComedyFunny, click Add.
• Add filter: Include in Dynamic Selections? is Yes, click Add.
• Click Search.
• Confirm results match:
  (Genre = Action OR Genre = ComedyFunny)
  AND Include in Dynamic Selections = Yes.