Add stable firmware-update notifications and connected-device nudge

[RCGV1]

Parent: meshtastic/design#124

Implement the stable firmware-update nudge for the connected local device, following the source-of-truth behavior in design#124 and the product workflow in Apple #2033.

Acceptance criteria

• Compare the connected device's reported version against the latest stable release using Meshtastic version ordering; do nothing for missing, malformed, equal, or newer current versions.
• Select the Android update flow or Meshtastic Flasher according to hardware capability, and name that destination in copy and accessibility metadata.
• Deliver at most one Android notification per (node identity, hardware target, stable version) after a successful connection; schedule a new one only for a newer stable release.
• Surface one non-dismissible, non-warning connected-device update nudge with the Material system_update_alt icon and an action to the selected destination.
• Clear the nudge on disconnect, device change, or once the node is current.
• Add targeted tests for ordering, eligibility, dedupe, destination selection, and update—not-warning—presentation. Attach emulator UI evidence; document any hardware verification that remains.