Make MCP server optional dependency

The fastmcp server code is now an optional dependency that can be
installed with the "mcp" extra. Core vector search functionality is
available without the MCP server dependency.

tests/test_mcp/test_mcp.py

@@ -0,0 +1,31 @@
+import json
+
+from fastembed import TextEmbedding
+from fastmcp import Client
+from mcp.types import TextContent
+
+
+async def test_call_tool(embedding_model: TextEmbedding, run_mcp: str):
+    input = "Quien es el mas guapo?"
+    collection = "dummy_collection"
+
+    embedding: list[float] = list(embedding_model.embed(input))[0].tolist()
+
+    client = Client(run_mcp)
+
+    async with client:
+        name = "semantic_search"
+        body = {"embedding": embedding, "collection": collection}
+        result = await client.call_tool(name, body)
+
+    content_block = result.content[0]
+
+    assert isinstance(content_block, TextContent)
+
+    deserialized_result = json.loads(content_block.text)
+
+    top_result = deserialized_result[0]
+
+    assert top_result["chunk_id"] == "0"
+    assert top_result["score"] > 0.7
+    assert top_result["payload"] == {"text": "Rick es el mas guapo"}