Allow manual Bedrock model ID input

Had claude help me define the issue I am having for you. Thanks for the awesome app

Issue:

IAM role has bedrock:InvokeModel but lacks bedrock:ListFoundationModels (enterprise restriction). Other apps like Cline VS code plugin allow manual model ID input (e.g., us.anthropic.claude-sonnet-4-5-20250929-v1:0) to bypass list fetch.

OS version: macOS 15.4 (Darwin 25.4.0)

BoltAI version: 2.9.2

Setapp user: Yes also a ios beta tester :-)

AI provider: AWS Bedrock with Profile Provider (AWS SSO), Region: us-east-1, Profile: bedrock-api-access

Steps to reproduce:

1. Open BoltAI → Add API Configuration

2. Select "Amazon Bedrock" as provider

3. Set Credential Source to "Profile Provider"

4. Set Region to "us-east-1"

5. Set Profile Name to "bedrock-api-access"

6. Click Next

7. Error: "Connection failed: Failed to fetch models from AWS Bedrock"

8. Cannot proceed - no option to manually enter model ID

Error message:

Connection failed: Failed to fetch models from AWS Bedrock

Request:

Allow manual model ID input option so users with restricted IAM permissions can proceed when festing models fails.