Support for model configuration from vscode settings

[pmfarsh]

Good design, but cloud model setup needs improvement

The extension has potential, but setting it up with AWS Bedrock Anthropic models was not possible. Configuring the model opens Claude in the terminal, causing settings to be lost.

Being able to configure models in VS Code's settings.json is great for custom model setups.

Example AWS Bedrock configuration:
json"claude-code.selectedModel": "au.anthropic.claude-sonnet-4-5-20250929-v1:0",
"claude-code.environmentVariables": [
{"name": "CLAUDE_CODE_SKIP_AUTH_LOGIN", "value": "1"},
{"name": "CLAUDE_CODE_USE_BEDROCK", "value": "1"},
{"name": "AWS_REGION", "value": "ap-southeast-2"},
{"name": "AWS_PROFILE", "value": "dev"},
{"name": "BEDROCK_MODEL_ID", "value": "au.anthropic.claude-sonnet-4-5-20250929-v1:0"},
{"name": "ANTHROPIC_MODEL", "value": "au.anthropic.claude-sonnet-4-5-20250929-v1:0"},
{"name": "ANTHROPIC_SMALL_FAST_MODEL", "value": "au.anthropic.claude-haiku-4-5-20251001-v1:0"}
]

Improvement needed:
AWS Bedrock configurations should persist without requiring terminal setup each time.