Add export-to-vault button to chat panel toolbar

[ScottKirvan]

Summary

The Export session to vault command is currently only accessible via the Command Palette (Ctrl+P) for the active session, and via the hover download icon in the Session Manager for past sessions.

A dedicated toolbar button in the chat panel would make this more discoverable.

Proposed behaviour

• Add a download/export icon button to the chat panel toolbar (next to the new-session button)
• Clicking it calls exportToVault() directly — same behaviour as Cortex: Export session to vault
• Button is disabled / hidden when there are no messages in the current session

Notes

• exportToVault() already exists in ClaudeView.ts — this is purely a UI addition
• The ephemeral name-detection query and "Preparing transcript…" notice are already wired in

[SKVFX-DevBot]

Picking this up. I'll add the export toolbar button to the chat panel. The exportToVault() function already exists — this is a UI-only addition.

Note: this issue has no priority label — flagging for triage as the label is missing.