feat: log Claude session ID in task logs

[bborn]

Summary

• Captures the Claude session ID from hook callbacks and logs it once per task execution
• Makes it easier to track and debug Claude sessions in the TUI task detail view
• Session ID is logged on the first hook call to avoid duplicate entries

Test plan

• Build passes (go build ./...)
• All tests pass (go test ./...)
• Manual test: Create a task, execute it, and verify the Claude session ID appears in the task logs

🤖 Generated with Claude Code