chore: add gpt-5.1 (#102)

Author: kujtimiihoxha

internal/providers/configs/openai.json

@@ -4,9 +4,65 @@
   "type": "openai",
   "api_key": "$OPENAI_API_KEY",
   "api_endpoint": "$OPENAI_API_ENDPOINT",
-  "default_large_model_id": "gpt-5-codex",
+  "default_large_model_id": "gpt-5-1-codex",
   "default_small_model_id": "gpt-4o",
   "models": [
+    {
+      "id": "gpt-5.1",
+      "name": "GPT-5.1",
+      "cost_per_1m_in": 1.25,
+      "cost_per_1m_out": 10,
+      "cost_per_1m_in_cached": 0.13,
+      "cost_per_1m_out_cached": 0.13,
+      "context_window": 400000,
+      "default_max_tokens": 128000,
+      "can_reason": true,
+      "reasoning_levels": [
+        "minimal",
+        "low",
+        "medium",
+        "high"
+      ],
+      "default_reasoning_effort": "medium",
+      "supports_attachments": true
+    },
+    {
+      "id": "gpt-5.1-codex",
+      "name": "GPT-5.1 Codex",
+      "cost_per_1m_in": 1.25,
+      "cost_per_1m_out": 10,
+      "cost_per_1m_in_cached": 0.25,
+      "cost_per_1m_out_cached": 0.25,
+      "context_window": 400000,
+      "default_max_tokens": 128000,
+      "can_reason": true,
+      "reasoning_levels": [
+        "minimal",
+        "low",
+        "medium",
+        "high"
+      ],
+      "default_reasoning_effort": "medium",
+      "supports_attachments": true
+    },
+    {
+      "id": "gpt-5.1-codex-mini",
+      "name": "GPT-5.1 Codex Mini",
+      "cost_per_1m_in": 0.25,
+      "cost_per_1m_out": 2,
+      "cost_per_1m_in_cached": 0.03,
+      "cost_per_1m_out_cached": 0.03,
+      "context_window": 400000,
+      "default_max_tokens": 128000,
+      "can_reason": true,
+      "reasoning_levels": [
+        "low",
+        "medium",
+        "high"
+      ],
+      "default_reasoning_effort": "medium",
+      "supports_attachments": true
+    },
     {
       "id": "gpt-5-codex",
       "name": "GPT-5 Codex",
@@ -31,8 +87,8 @@
       "name": "GPT-5",
       "cost_per_1m_in": 1.25,
       "cost_per_1m_out": 10,
-      "cost_per_1m_in_cached": 0.25,
-      "cost_per_1m_out_cached": 0.25,
+      "cost_per_1m_in_cached": 0.13,
+      "cost_per_1m_out_cached": 0.13,
       "context_window": 400000,
       "default_max_tokens": 128000,
       "can_reason": true,