Fix: add email-validator, remove gradio from requirements

requirements.txt

@@ -7,7 +7,8 @@
 # ── Core Framework ────────────────────────────────────────
 fastapi==0.115.9
 uvicorn[standard]==0.32.1
-pydantic==2.10.6
+pydantic[email]==2.10.6
+email-validator==2.1.1
 pydantic-settings==2.7.1
 
 # ── Database ──────────────────────────────────────────────
@@ -34,8 +35,6 @@ tiktoken==0.7.0
 chromadb==0.5.0
 numpy==1.26.4                  # chromadb 0.5.x incompatible with NumPy 2.x
 
-# ── Hugging Face UI ───────────────────────────────────────
-gradio==5.9.1
 
 # ── Free Local ML Models ──────────────────────────────────
 sentence-transformers==3.0.1   # MiniLM intent + book confidence