Add Full-Text Search for Puzzles

[Mkalbani]

Description

Integrate full-text search into the puzzles module so players can discover puzzles by keyword, concept, or description. As the puzzle library grows, filtering alone becomes insufficient — players need to search across titles, descriptions, and categories in a single query. The implementation should be performant and return relevance-ranked results.

Acceptance Criteria

• GET /puzzles/search?q= accepts a search query and returns ranked results
• Search spans puzzle title, description, and category name
• PostgreSQL full-text search (tsvector/tsquery) or a dedicated search index is used
• Results are paginated and include a relevance score in the response
• Filtering by difficulty and category can be combined with the search query
• Empty queries fall back to the standard paginated list endpoint
• Search queries under 2 characters return a 400 with a descriptive message
• Unit tests cover relevant matches, empty queries, combined filters, and short query rejection

[Dickson2015]

The issue description is crystal clear. Maintainer I would love to work on this issue.

[Primex-hub]

I will love to fix this issue

[grantfox-oss]

🦊 GrantFox — @Dickson2015 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #75)
2. Your PR will be reviewed by the MindFlowInteractive maintainers

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