🎨 Palette: Keyboard Shortcuts for Session Summary

[godie]

💡 What: Added keyboard shortcuts and discoverability hints to the V2 Session Summary page.
🎯 Why: To streamline the user loop for high-traffic terminal screens, allowing users to quickly start new sessions or navigate to the dashboard/errors without reaching for the mouse.
♿ Accessibility: Added bracketed visual hints to button labels, and updated aria-label and title attributes to explicitly mention the available shortcuts for screen readers and mouse users.
✅ Testing: Created a new unit test suite (V2SessionSummary.test.jsx) and verified visually via Playwright.

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PR created automatically by Jules for task 2367168421785504352 started by @godie

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