feat: Implement State pattern for camera logic

Refactor camera control logic in `MainController` to use the State design pattern.

- Create a new `core/camera/states.py` module with state classes (`NoCamerasState`, `DetectingState`, `ReadyToStreamState`, `StreamingState`).
- `MainController` now acts as a context, delegating actions to the current state object.
- This replaces complex conditional logic with a robust, scalable, and maintainable state machine, making it easier to manage camera behavior and add new states in the future.

core/camera/states.py

@@ -0,0 +1,57 @@
+from __future__ import annotations
+from abc import ABC, abstractmethod
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from controllers.main_controller import MainController
+
+class CameraState(ABC):
+    """Abstract base class for all camera states."""
+
+    def enter_state(self, controller: MainController):
+        """Called upon entering the state, e.g., to update the UI."""
+        pass
+
+    @abstractmethod
+    def handle_start_button(self, controller: MainController):
+        """Handles the main camera button click."""
+        pass
+
+class NoCamerasState(CameraState):
+    def enter_state(self, controller: MainController):
+        controller.welcome_view.set_button_text("Wykryj kamery")
+        controller.welcome_view.set_info_text("Nie wykryto kamer. Kliknij, aby rozpocząć.")
+        controller.welcome_view.camera_start_btn.setEnabled(True)
+
+    def handle_start_button(self, controller: MainController):
+        controller.camera_detect()
+
+class DetectingState(CameraState):
+    def enter_state(self, controller: MainController):
+        controller.welcome_view.set_button_text("Wykrywanie...")
+        controller.welcome_view.set_info_text("Trwa wykrywanie kamer...")
+        controller.welcome_view.camera_start_btn.setEnabled(False)
+
+    def handle_start_button(self, controller: MainController):
+        # Do nothing while detecting
+        pass
+
+class ReadyToStreamState(CameraState):
+    def enter_state(self, controller: MainController):
+        cameras = controller.camera_manager.get_detected_cameras()
+        controller.welcome_view.set_button_text("Uruchom kamerę")
+        controller.welcome_view.set_info_text(f"Wykryto {len(cameras)} kamer(y).")
+        controller.welcome_view.camera_start_btn.setEnabled(True)
+
+    def handle_start_button(self, controller: MainController):
+        controller.start_liveview()
+
+class StreamingState(CameraState):
+    def enter_state(self, controller: MainController):
+        controller.welcome_view.set_button_text("Zatrzymaj kamerę")
+        controller.welcome_view.camera_start_btn.setEnabled(True)
+        if controller.split_view.stack.currentWidget() != controller.live_view:
+            controller.split_view.toggle_live_view()
+
+    def handle_start_button(self, controller: MainController):
+        controller.stop_liveview()