🐛 Fix standardize exact matches

[Zethson]

Related to @felix0097 issue

The newly added test failed before and is what he ran into in his instance. The new implementation:

1. Explicitly calculates unmatched terms by comparing the input identifiers (mapped_df["__agg__"]) with the field_map.index.
2. If all terms match directly, synonym mapping and other fallback logic are skipped entirely, preserving the correct results for Plasmablast and cDC.

[falexwolf]

Great!

I'm curious: is the "search on synonyms" logic duplicated across lamindb and bionty? If so, is there still any reason to have this after integrating bionty with lamindb? (I guess this is mostly a question for @sunnyosun)

[Koncopd]

I think it doesn't matter much as i will also port the search logic from lamindb to bionty soon.

[falexwolf]

I think it doesn't matter much as i will also port the search logic from lamindb to bionty soon.

That means it's in fact duplicated right now, which was evidently very error prone. Good that this gets consolidated.

[sunnyosun]

Looks good!