Support 1M tokens for anthropic (drive-by: make aws bedrock secondary… (#1233)

… provider)
    
<!-- This is an auto-generated description by cubic. -->
---

## Summary by cubic
Enables 1M-token context for Anthropic Claude 4 Sonnet and marks AWS
Bedrock as a secondary provider. Adds the required Anthropic beta header
and updates model metadata and pricing indicator.

- **New Features**
- Send header anthropic-beta: context-1m-2025-08-07 when using the
Anthropic provider.
- Update Claude 4 Sonnet configs: contextWindow to 1,000,000; add cost
warning; increase pricing tier to 5 (applies to Anthropic and Bedrock
model IDs).
  - Set AWS Bedrock as a secondary provider.

<!-- End of auto-generated description by cubic. -->

src/ipc/handlers/chat_stream_handlers.ts

@@ -686,6 +686,7 @@ This conversation includes one or more image attachments. When the user uploads
           const providerId = modelClient.builtinProviderId;
           const isVertex = providerId === "vertex";
           const isGoogle = providerId === "google";
+          const isAnthropic = providerId === "anthropic";
           const isPartnerModel = selectedModelName.includes("/");
           const isGeminiModel = selectedModelName.startsWith("gemini");
           const isFlashLite = selectedModelName.includes("flash-lite");
@@ -707,8 +708,12 @@ This conversation includes one or more image attachments. When the user uploads
               },
             } satisfies GoogleGenerativeAIProviderOptions;
           }
-
           return streamText({
+            headers: isAnthropic
+              ? {
+                  "anthropic-beta": "context-1m-2025-08-07",
+                }
+              : undefined,
             maxOutputTokens: await getMaxTokens(settings.selectedModel),
             temperature: await getTemperature(settings.selectedModel),
             maxRetries: 2,