Preserve expanded drive-history groups

[ahernsean]

Summary

• Preserve expanded drive-history groups across navigation and browser back.
• Apply the behavior to every grouping mode using URL-scoped session state.
• Add browser regression coverage for all grouping options.
• Clarify that Rocky uses containerized WebKit first and requires escalation/retry before Chromium fallback.

Validation

• CI-equivalent static checks passed.
• Non-browser suite: 110 passed, 4 deselected; coverage 95.10%.
• Browser Chromium fallback: 4 passed.
• git diff --check passed.

The local containerized WebKit procedure was not run in this PR validation; Chromium was used after the earlier sandbox loopback failure.