Feature Request: Tool whitelist for Interactive Mode

### Describe the feature or problem you'd like to solve

Currently Interactive mode requires manual approval for every tool call, including safe read-only operations (grep, cat, find, git log, git status, etc.). The only alternative is /allow-all which also approves destructive operations.

### Proposed solution

Add a persistent allowed_tools whitelist in ~/.copilot/config.json, similar to how antigravity handles tool permissions. Users can pre-approve safe, non-modifying
commands and only be prompted for dangerous operations (file writes, deletes, shell commands that modify state).

### Example prompts or workflows

{
"allowed_tools": ["bash:grep", "bash:find", "bash:cat", "bash:git log", "bash:git status", "view", "glob"]
}

### Additional context

_No response_