feat(models): add bedrock-converse-stream API type

Add AWS Bedrock Converse Stream API to the list of supported model APIs,
enabling custom provider configurations for Amazon Bedrock endpoints.

This allows users to configure Bedrock models in their clawdbot.json:

  "models": {
    "providers": {
      "amazon-bedrock": {
        "baseUrl": "https://bedrock-runtime.us-east-1.amazonaws.com",
        "api": "bedrock-converse-stream",
        "models": [...]
      }
    }
  }

The underlying adapter already exists; this change exposes it as a valid
configuration option.

src/config/types.models.ts

@@ -3,7 +3,8 @@ export type ModelApi =
   | "openai-responses"
   | "anthropic-messages"
   | "google-generative-ai"
-  | "github-copilot";
+  | "github-copilot"
+  | "bedrock-converse-stream";
 
 export type ModelCompatConfig = {
   supportsStore?: boolean;

src/config/zod-schema.core.ts

@@ -8,6 +8,7 @@ export const ModelApiSchema = z.union([
   z.literal("anthropic-messages"),
   z.literal("google-generative-ai"),
   z.literal("github-copilot"),
+  z.literal("bedrock-converse-stream"),
 ]);
 
 export const ModelCompatSchema = z