Fix primitive network credential handling

[HANCORE-linux]

Summary

• route Wi-Fi credential actions from primitive snapshots without retaining backend objects
• revalidate visible identities, security, connection state, and saved-profile eligibility at mutation time
• preserve the active credential delegate across scanner refreshes and restore panel keyboard control after cancellation
• align the shared Shibumi panel host with Quattro's bounded keyboard-focus prime
• retain saved-only profile actions and strict one-to-one profile matching

Validation

• installed-source-parity network regression
• forward-compat network regression
• complete contract regression
• shared and bar-host vendoring checks
• package, suite, health, manager, and AUR scaffold gates
• independent code review: no actionable findings
• Machine 2 full beta.8 suite transaction and cold start: one Quickshell process, no QML or plugin load errors
• Machine 2 visual acceptance: credential focus survived scanner refreshes; Cancel restored keyboard navigation; presentation unchanged

No credentials were submitted, logged, or stored during validation, and no Wi-Fi connection was changed.

Addresses #25.