feat(network): harden NetworkManager layer for 24/7 reliability

[gmmcosta15]

Description

• Feature
• Bug fix
• Code refactor

Hardens the network layer for 24/7 operation and makes Wi-Fi recovery reliable enough that a user can always get back online to update. Stays fully async on sdbus signal watching.

• Enforce one active link at a time (Wi-Fi, ethernet or hotspot), on user toggles only; background handlers never drop a link.
• Persist ethernet-off intent in the wired profile so an NM restart stops resurrecting the cable.
• Detect hotspot from NM's 802.11 device mode, not an SSID match, so an externally started AP is no longer reported as a client connection.
• Recover from stale D-Bus device paths by re-detecting interfaces and retrying the signal map.
• Arm the loading guard before issuing link changes, fixing a toggle that bounced back OFF during ethernet teardown.
• Support fully disabling the radio, including rfkill, with a recovery path back to a working link.
• Classify PSK and unknown auth failures instead of hanging with an empty network list on a wrong password.
• Full-screen numeric keyboard for IP, mask and gateway fields, restyled to match the UI.
• Cut complexity (no function above C901 threshold 10) and drop per-poll debug logs that spammed the log directory.

Tests

Coverage: models.py 100%, manager.py 99%, keyboardPage.py 90%, networkWindow.py 87%, worker.py 70%.

Future work

• Radio-cycling phases (Wi-Fi off/on, rfkill, hotspot return to client mode, static IP rewrite) need a run with console or ethernet access. AP-mode hotspot detection is deployed and does not regress client mode, but its assertion lives in a skipped phase.
• The toggle-bounce fix is UI-driven and has no automated coverage; needs a manual pass on the screen.
• Coalesce the redundant _build_signal_map fan-out.
• Stale-path recovery logs the same warning twice at an identical timestamp; cosmetic.
• NameOwnerChanged would be a cleaner NM-restart trigger.
• Structural split of worker.py, still large after the complexity work.

[gmmcosta15]

dived into #308, #309 , #310 , #311 , #312