feat(search-history): add sharing functionality for saved searches, database schema

[sreeshanth-soma]

Closes: #103

Summary

Implements Shared Saved Searches so users can share saved advanced searches with specific users or permission groups.

Recipients see shared searches under a new Shared With Me section and can execute them directly from Search History.

Problem

Issue #103 requested a way to share saved searches from the Search History/My Searches UI so other users (or group members) can reuse them.
Previously, searches were private to each user (saved / history) with no sharing mechanism.

Changes

Backend — core/models/media_model.php

Added sharing model support:

• search_share():
  • Validates ownership + saved type
  • Replaces existing share rows for a search
  • Inserts user/group recipient rows
• search_unshare()
• search_get_shared():
  • Returns searches shared with current user directly or via group membership
  • Includes shared_by_name attribution
  • Safely returns [] when no shared rows exist
• search_get_shared_recipients() helper

Backend — core/controllers/media.php

Added/updated API endpoints:

• media_my_searches() now returns:
  • saved
  • history
  • shared
• New media_my_searches_share() endpoint (POST /v2/media/searches/share)
• New media_my_searches_unshare() endpoint (DELETE /v2/media/searches/share/:id)

Database — core/updates/20260219.php

Added migration to create media_searches_shared table with:

• search_id
• shared_by
• shared_with_user_id
• shared_with_group_id
• indexes and cascading foreign keys

Note:

• shared_with_group_id uses unsigned int to match users_groups.id type.

Frontend — public/html/sidebar/my_searches.html

• Added new Shared With Me section.
• Added Share item in saved-search context menu.
• Added shared-search context menu (Search action).

Frontend — public/html/sidebar/share_search.html

New modal UI:

• Multi-select users
• Multi-select groups
• Share / Cancel actions

Frontend — public/js/sidebar.js

Added/updated sidebar behavior:

• Render shared searches returned by API
• Support unique IDs for shared items (avoid collisions with saved IDs)
• Fix context-menu targeting for shared items
• Ensure shared item click/search resolves the correct filters
• Added mySearchesShareWindow() and mySearchesShareSubmit()
• Added shared attribution display (Shared by: <name>) with improved visual separation

Verification Steps

• Log in as User A.
• Create and save an advanced search.
• Open Search History, right-click saved search, click Share.

• Select User B and/or a group, then submit.

• Log in as User B.
• Open Search History and verify search appears under Shared With Me.
• Click shared search and verify correct filters execute.
• Right-click shared search and run via context menu; verify same result.

The Result:

• Verify no API warning/error when there are no shared searches.
• Verify existing Saved/Search History/default-search flows still work as before.