feat: extend smart search, match exif-description too

[TheHamkerCat]

Adding a feature to search images based on description.

I've extended /search/smart instead of creating /search/description, implemented due to personal need but wanted to share so everyone can benefit. Feedback welcome!

changelog:
When searching "beach vacation", results will first show images that have "beach vacation" in their description, and then visually similar images by embeddings (past behavior)

[mertalev]

Thanks for the PR! This has been a much-requested feature that I'm sure will bring a smile to many faces. There are some changes that need to be made first, though.

You should create a trigram index and adjust this query to use it. They perform better, both for search time, finding results and in working with different languages. You can see searchPlaces and the migrations containing "admin1Name" etc. to get an idea of how to do this. npm run typeorm:migrations:create will create an empty migration file to add the index. Also use the f_unaccent function like the other indices.

The query will also need to be restructured. As written, it will do a brute force search on both all embeddings and all exif rows. This is a more performant way to write this query as it lets both text and embeddings leverage indices for the bulk of the query and rerank on a much smaller set of rows. You can make the query from searchAssetBuilder its own CTE that the other two CTEs reference.

[TheHamkerCat]

Thanks @mertalev will do this on weekend!

[mertalev]

Sounds good! I'd also like to mention that we're changing from TypeORM to Kysely very soon (#12857), so it may be the case that the change happens before this PR is merged. The DB migration won't be affected by this, but the searchSmart changes would need to be refactored to use Kysely if this happens. Feel free to continue working on this PR if this is fine for you. Otherwise, you might want to wait until that PR is merged.

[TheHamkerCat]

I'll wait for it to be merged in that case, will be easier for me since I'm not that much familiar with the codebase.