feat: add Ollama embedder with batching and retries

tests/test_embedder.py

@@ -0,0 +1,21 @@
+import pytest
+import respx
+from httpx import Response
+
+from companion.rag.embedder import OllamaEmbedder
+
+
+@respx.mock
+def test_embed_batch():
+    route = respx.post("http://localhost:11434/api/embed").mock(
+        return_value=Response(200, json={"embeddings": [[0.1] * 1024, [0.2] * 1024]})
+    )
+    embedder = OllamaEmbedder(
+        base_url="http://localhost:11434", model="mxbai-embed-large", batch_size=2
+    )
+    result = embedder.embed(["hello world", "goodbye world"])
+    assert len(result) == 2
+    assert len(result[0]) == 1024
+    assert result[0][0] == 0.1
+    assert result[1][0] == 0.2
+    assert route.called