feat: change default model from olmOCR to Gemini 3 Pro Preview

Update default LLM backend from olmOCR-2-7B to gemini-3-pro-preview and consolidate Gemini model configuration. Remove duplicate gemini-3-pro-preview entry from MODELS_MAP and update MODEL_GEMINI constant to use the pro preview variant.

- Change default model_selector value from MODEL_OLMOCR to MODEL_GEMINI
- Update MODEL_GEMINI constant from "gemini-2.5-flash" to "gemini-3-pro-preview"
- Consolidate gemini-3-pro-preview pricing ($

app.py

@@ -141,7 +141,7 @@ def build_interface() -> gr.Blocks:
                 model_selector = gr.Dropdown(
                     label="LLM backend",
                     choices=list(MODELS_MAP.keys()),
-                    value=MODEL_OLMOCR,
+                    value=MODEL_GEMINI,
                 )
 
                 prompt_editor = gr.Textbox(

common.py

@@ -1,4 +1,4 @@
-MODEL_GEMINI = "gemini-2.5-flash"
+MODEL_GEMINI = "gemini-3-pro-preview"
 MODEL_OLMOCR = "olmOCR-2-7B-1025-FP8"
 
 
@@ -19,8 +19,7 @@ MODELS_MAP = {
     "gpt-4.1-mini": {"input": 0.40, "output": 1.60, "backend": "openai"},
     "gpt-4.1-nano": {"input": 0.10, "output": 0.40, "backend": "openai"},
     # Other backends (mock rates)
-    MODEL_GEMINI: {"input": 0.30, "output": 2.50, "backend": "gemini"},
-    "gemini-3-pro-preview": {"input": 2.00, "output": 12.00, "backend": "gemini"},
+    MODEL_GEMINI: {"input": 2.00, "output": 12.00, "backend": "gemini"},
     MODEL_OLMOCR: {"input": 1.35, "output": 0.30, "backend": "olmocr"},
     "gemini-2.5-pro": {"input": 1.25, "output": 10.00, "backend": "gemini"},
     "default": {"input": 2.50, "output": 10.00, "backend": "openai"},