fix: Refactor DConfig wrapper class generation for thread safety and lifecycle management

Problem:
- Single-threaded design with weak state machine (Invalid -> Succeed/Failed)
- No proper handling of object destruction during initialization
- Signal emissions in worker thread context (incorrect thread context)
- Fragile destructor unable to handle all cleanup scenarios

Solution:
1. Introduce Data layer separation (TreelandUserConfigData + TreelandUserConfig)
   - Clear separation between internal data management and public API
   - Enables safer object lifecycle management

2. Enhance state machine (3-state -> 5-state model)
   - Add Initializing and Destroyed states
   - Use atomic CAS operations for thread-safe state transitions
   - States: Invalid -> Initializing -> (Succeed | Failed | Destroyed)

3. Improve async initialization and cleanup
   - Use QPointer for safe backref checks (prevent use-after-free)
   - Support 4 destruction paths: normal/failed/quick/mid-initialization
   - Atomic state transitions with proper signal emission guards

4. Separate thread responsibilities
   - updateValue(): Worker thread reads config values
   - updateProperty(): Main thread updates properties and emits signals
   - Use QMetaObject::invokeMethod for correct thread context

Improvements:
- Thread safety: Complete atomic operations coverage
- Memory safety: QPointer guards prevent dangling pointers
- Code clarity: Layered architecture with clear responsibilities
- Backward compatibility: API unchanged

Author: Dami-star