fix: support ModernBertModel architecture

[mikemikimike]

Summary

Closes #214.

TextEmbedder::from_pretrained_hf rejected Hugging Face checkpoints whose architecture is ModernBertModel, even though the existing ModernBERT embedder supports them directly.

This change routes both ModernBertModel and the existing ModernBertForMaskedLM architecture through the same ModernBertEmbedder construction path. A focused unit test covers both accepted architecture names and confirms unrelated architectures are not matched.

Validation

• cargo test -p embed_anything supports_modernbert_embedding_architectures --lib — passed (1 test).
• git diff --check — passed.
• cargo fmt --all -- --check reports pre-existing formatting differences outside the changed file; rustfmt --edition 2021 rust/src/embeddings/embed/text.rs was applied to the changed file.
• cargo clippy -p embed_anything --lib --tests -- -D warnings was started in an isolated target directory; compilation was still in progress during handoff on Windows.