[Store] Add configurable semantic ratio to Meilisearch Store

[ahmed-bhs]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	nope
Deprecations?	no
Tests pass?	yes
Fixed tickets	#93
License	MIT
Doc PR	no

This PR drops a new configurable semanticRatio parameter into the Meilisearch Store. It's all about letting you fine-tune the vibe between classic full-text search and the new-school semantic (vector) search in Meilisearch's hybrid setup.

Right now, the ratio is hardcoded to 1.0 (100% semantic), which is a bit rigid. This change gives you the freedom to slide between super-precise full-text matches and more conceptual. For anyone curious about the nitty-gritty, Meilisearch has a great article on [Full-Text Search vs. Vector Search].

It's fully backward-compatible, defaulting to 1.0, so no old code gets broken.

Example Usage

1. Set the vibe on instantiation:

// A perfect 50/50 split
$store = new Store(..., semanticRatio: 0.5);

2. Override it for a specific query:

// Let's go old-school: pure full-text search for this one
$results = $store->query($vector, [
    'semanticRatio' => 0.0,
    'q' => 'PHP 8.2', // The text query for full-text matching
]);

Now end users can configure the semantic ratio in their config/packages/ai.yaml:

  ai:
      store:
          meilisearch:
              my_store:
                  endpoint: '%env(MEILISEARCH_URL)%'
                  api_key: '%env(MEILISEARCH_API_KEY)%'
                  index_name: 'my_index'
                  semantic_ratio: 0.5  # 50/50 hybrid search

[Guikingone]

Don't forget to add the support for the option in AiBundle.php, as you can configure it in the constructor, end users must be in capacity of configuring it via the semantic configuration 🙂

[OskarStark]

I think we have ->min() and ->max(), can you please check. Unsure if we have ->between()

[ahmed-bhs]

Yes @OskarStark, it is cleaner using min and max, but unfortunately, a between function doesn't exist in the symfony/config component.