chore(presets): align Code0 and Qiniu Gemini defaults to 3.6 Flash

Both presets pinned gemini-3.1-pro-preview while the other Gemini presets
had moved to gemini-3.6-flash. Note this is a tier change rather than a
version bump: there is no 3.6 Pro release and 3.5 Pro is still limited to
partner testing, so the current baseline is a flash-tier model.

The gemini-3.1-pro-preview row in the built-in pricing seed is kept so
historical usage keeps its cost.

src/config/geminiProviderPresets.ts

@@ -234,11 +234,11 @@ export const geminiProviderPresets: GeminiProviderPreset[] = [
     settingsConfig: {
       env: {
         GOOGLE_GEMINI_BASE_URL: "https://code0.ai",
-        GEMINI_MODEL: "gemini-3.1-pro-preview",
+        GEMINI_MODEL: "gemini-3.6-flash",
       },
     },
     baseURL: "https://code0.ai",
-    model: "gemini-3.1-pro-preview",
+    model: "gemini-3.6-flash",
     description: "Code0",
     category: "aggregator",
     isPartner: true,
@@ -360,11 +360,11 @@ export const geminiProviderPresets: GeminiProviderPreset[] = [
     settingsConfig: {
       env: {
         GOOGLE_GEMINI_BASE_URL: "https://api.qnaigc.com/bypass/vertex",
-        GEMINI_MODEL: "gemini-3.1-pro-preview",
+        GEMINI_MODEL: "gemini-3.6-flash",
       },
     },
     baseURL: "https://api.qnaigc.com/bypass/vertex",
-    model: "gemini-3.1-pro-preview",
+    model: "gemini-3.6-flash",
     description: "Qiniu",
     category: "aggregator",
     isPartner: true,