Epic: [ACP] Tool call lifecycle improvements

[bug-ops]

Objective

Improve tool call status reporting and terminal execution robustness.

Scope

• Emit InProgress status before tool execution, Completed/Error after
• Add terminal command timeout with kill_terminal_command
• Emit ToolCallContent::Terminal for shell results (IDE inline embedding)

Acceptance Criteria

• Tool calls report InProgress -> Completed/Error lifecycle
• Terminal commands have configurable timeout
• Shell tool calls use Terminal content variant