Extract hardware controller lifecycle from MainWindow into HardwareManager service

[ny4i]

Problem

MainWindow directly creates and wires all hardware controllers (RadioController, AmplifierController, RotatorController, KeyerController, IambicKeyer). Each adds ~10-20 lines of construction, signal wiring, and auto-connect logic. This contributes to MainWindow bloat (currently 5,050+ lines, well over the 3,000 STOP limit).

Current State

All four hardware controllers follow the same pattern in MainWindow:

1. Create controller instance
2. Wire signals (connection status, state updates)
3. Check AppSettings for auto-connect
4. Initiate async connection if enabled

Files affected:

• src/ui/MainWindow.cpp lines ~1160-1240 (amplifier, rotator, keyer creation)
• src/ui/MainWindow.h (member variables: m_amplifierController, m_rotatorController, m_keyerController, m_iambicKeyer)

Proposed Solution

Create HardwareManager service class that:

• Owns all hardware controllers (RadioController, AmplifierController, RotatorController, KeyerController, IambicKeyer)
• Handles construction, signal wiring, auto-connect logic
• Exposes controllers via getters for other services/dialogs that need them
• Follows existing service patterns (e.g., AmplifierService, RotatorService)

class HardwareManager : public QObject {
    Q_OBJECT
public:
    explicit HardwareManager(QObject* parent = nullptr);
    
    RadioController* radioController() const;
    AmplifierController* amplifierController() const;
    RotatorController* rotatorController() const;
    KeyerController* keyerController() const;
    IambicKeyer* iambicKeyer() const;
    
    void initializeFromSettings();  // Read AppSettings, create controllers, auto-connect
    
signals:
    void radioConnectionChanged(bool connected);
    void amplifierConnectionChanged(bool connected);
    // etc.
};

MainWindow would then hold a single HardwareManager* instead of 5+ individual controller pointers.

Acceptance Criteria

• All hardware controller creation moved out of MainWindow
• All auto-connect logic moved out of MainWindow
• MainWindow only holds HardwareManager*, accesses controllers via getters
• No behavioral changes (all signals still reach the same destinations)
• Existing tests still pass

[ny4i]

Updated Scope — Absorbs #73

This issue now includes the radio command dispatch from #73 (closed). HardwareManager should own:

1. Hardware lifecycle (original scope): construction, signal wiring, auto-connect for RadioController, AmplifierController, RotatorController, KeyerController/IambicKeyer
2. Radio command dispatch (from Refactor: Move radio control logic from event handlers to RadioControlFacade #73): increaseCwSpeed(), decreaseCwSpeed(), abortCw(), toggleTransmit() etc. — extracted from MainWindow's keyPressEvent/eventFilter

Execution Order

This is Step 2 in the MainWindow extraction plan:

1. Refactor: Extract business logic from MainWindow into use-case classes #71 (Use-Case Extraction) — do first, highest payoff
2. Extract hardware controller lifecycle from MainWindow into HardwareManager service #83 (HardwareManager + RadioControlFacade) — this issue, do second
3. Refactor: Introduce SessionController to own non-UI services #70 (SessionController) — do last, composes the extracted subsystems

Convention

All extracted code must use constructor injection (no new AppSettings::instance() or other singleton calls). This replaces the standalone #77 which was closed.