Fix 'Start Chat' from bash quick actions when no chat is open

[mcintyre94]

Summary

• When running bash from Quick Actions outside a chat (e.g. Overview tab), the "Start Chat" button was silently broken — it guarded on an existing chatViewModel being non-nil and did nothing if no chat was open
• Now it always creates a new chat, switches to it, and pre-fills the input bar with the formatted command output (same pattern as "Insert into chat" from within a chat)
• The user lands on the new chat with the bash output ready in the text field, so they can type their question and send it to Claude

Test plan

• On the Overview tab, open Quick Actions → Bash tab
• Run a command and wait for output
• Tap "Start Chat" — should navigate to chat tab with a new chat, bash output pre-filled in the input bar
• Verify "Insert into chat" from within a chat still works as before

🤖 Generated with Claude Code

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.