Add e2e coverage for session vfolder mount and dot-automount

Covers mounting a folder – including a dot-prefixed automount – from the session launcher through to the session detail drawer's Mounted Folders section, exercised with a real session launch and terminate.

File: `e2e/session/session-vfolder-mount.spec.ts`. Verified: 7 passed (5 tests + 2 cleanup).

JIRA Issue: FR-3298

Start with e2e/session/session-vfolder-mount.spec.ts and run its existing end-to-end tests to understand the session launcher and session detail drawer flow. Verify coverage for mounting a regular folder and a dot-prefixed automount, including the Mounted Folders section, real session launch, and termination; done means all tests and cleanup pass.

Written by the indexing model from the issue text.