Lambda prompt (λ) appears in interactive sessions with workspace chat.defaultAgent

[puneetpjl]

Description:
When running kiro-cli chat --trust-all-tools in an interactive terminal session, the prompt incorrectly shows the lambda symbol [MyAgent] λ !> instead of
the standard interactive prompt [MyAgent] !>.

The lambda symbol should only appear when the agent is invoked programmatically (e.g., via shell scripts), not during normal interactive chat sessions.

Steps to Reproduce:

1. Navigate to a workspace directory (e.g., ~/my-project/)

2. Create workspace-specific Kiro settings: .kiro/settings/cli.json

3. Add the following content:
   json
   {
   "chat.defaultAgent": "MyAgent"
   }

4. Run kiro-cli chat --trust-all-tools from that directory

5. Observe the prompt shows [MyAgent] λ !> with the lambda symbol

Expected Behavior:
The prompt should display [MyAgent] !> (without lambda symbol) for interactive terminal sessions, regardless of workspace settings.

Actual Behavior:
The prompt displays [MyAgent] λ !> (with lambda symbol), incorrectly indicating programmatic/non-interactive mode.

Environment:

• Kiro CLI version: 1.25.1
• OS: macOS
• Agent: Custom agent
• Setting location: Workspace-specific .kiro/settings/cli.json