feat(network): NetworkManager refactor and NetworkControlWindow rewrite

[gmmcosta15]

Description

Select the type:

• Feature
• Bug fix
• Code refactor
• Documentation

This PR delivers a complete refactor of the NetworkManager subsystem and the
NetworkControlWindow, replacing the monolithic lib/network.py with a clean
manager/worker architecture. It also incorporates all changes from PR #168
(hotspot QR code) and PR #178 (hotspot config file persistence), which were
never merged to dev.

• lib/network/manager.py — NetworkManager(QObject): main-thread-safe
  interface. Submits coroutines to the worker's asyncio loop; emits pyqtSignal
  for state, scan results, connection outcome, connectivity, hotspot config, and
  errors. Includes a 5-minute keepalive timer as a safety net for missed D-Bus
  signals.
• lib/network/worker.py — NetworkManagerWorker: daemon thread owning the
  asyncio loop and D-Bus connection. Signal-reactive (no polling); 0.8 s debounce
  for rapid NM signal bursts.
• lib/network/models.py — frozen dataclasses and enums: NetworkInfo,
  SavedNetwork, NetworkState, ConnectivityState, SecurityType,
  HotspotConfig, VlanInfo, ConnectionPriority, etc.
• lib/panels/networkWindow.py — NetworkControlWindow rewritten against the
  manager API: hidden network page, VLAN/DHCP flow, network priority management,
  hotspot QR code, update page.
• lib/panels/mainWindow.py — wired to the new NetworkManager.
• lib/qrcode_gen.py — updated to accept hotspot SSID/password/security.
• configfile.py — added edit_option / get_option helpers for
  BlocksScreen.cfg (used by hotspot persistence).
• SVG icons reorganised from btn_icons/ into btn_icons/network/; added
  ethernet_connected.svg and static_ip.svg; removed internet_cable.svg
  from the top-bar resources.
• lib/ui/wifiConnectivityWindow.ui and wifiConnectivityWindow_ui.py — deleted
  (replaced by the new window implementation).
• list_model.py refactored for the new network list view.
• pytest.ini — added project-wide pytest configuration (qt_api=pyqt6,
  asyncio_mode=auto, integration marker gating).
• scripts/requirements.txt / scripts/requirements-dev.txt — updated
  dependencies.
• tests/network/ — unit tests for manager (72 tests, 100 % coverage), worker,
  models, and a gated sdbus integration test suite; UI tests for
  NetworkControlWindow.
• tests/util/ — unit tests for list_model and qrcode_gen.

Motivation

The original lib/network.py (≈1 550 lines) mixed D-Bus I/O, Qt signal
emission, threading concerns, and business logic in a single file, making it
hard to test, maintain, and extend. The new architecture separates concerns
strictly:

• Testability: the manager and worker can be tested in isolation with mock
  D-Bus proxies — no real NetworkManager required for unit tests.
• Thread safety: all D-Bus work runs on the asyncio thread; all Qt widget
  updates run on the main thread via queued pyqtSignal delivery.
• Reliability: signal-reactive model (no polling) with debounce; keepalive
  timer guards against missed D-Bus signals; connection timeout increased to 20 s
  to handle WPA3/Nokia routers.
• Hotspot persistence (from PR Feat/hotspot qrcode #168 and PR Feature hotspot config file #178): SSID and password survive
  reboots via BlocksScreen.cfg; QR code displayed on the hotspot panel.

Tests

• pytest tests/network/ — unit + UI tests, all pass.
• python -m pytest tests/network/test_manager_unit.py --cov=BlocksScreen.lib.network.manager --cov-report=term-missing — manager.py at 100 %.
• Integration tests (NM_INTEGRATION_TESTS=1 pytest -m integration tests/network/)
  require a real NetworkManager and are excluded from CI by default.

Test configuration: pytest.ini, qt_api=pyqt6, asyncio_mode=auto,
QT_QPA_PLATFORM=offscreen.

Co-Authors

Co-author: @Robert0Mart