fix: ship stability-critical recovery and sidebar fixes

[arzafran]

Summary

• recover only live terminal sessions and fully tear down closed-window resources
• fix owning-window sidebar controls, move themes to Appearance, and show provider usage on demand
• preserve browser history/import/download data and reduce background telemetry/logging work
• harden Mobile Bridge admission, revocation, and shutdown

Verification

• isolated tagged Debug build: release-critical-final
• independent committed-diff review: approved with no P0/P1 findings
• runtime, compatibility, UI, and release dry-run checks will run in GitHub Actions

Held for follow-up

• update-relaunch synchronization (persistence ordering/deadlock design unresolved)
• browser automation/state-transfer races
• release workflow overhaul, broad socket actor migration, and Ghostty clipboard work