initial structure implemented

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_docs/02_components/helpers/h01_camera_model_spec.md

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+# Camera Model Helper
+
+## Interface Definition
+
+**Interface Name**: `ICameraModel`
+
+### Interface Methods
+
+```python
+class ICameraModel(ABC):
+    @abstractmethod
+    def project(self, point_3d: np.ndarray, camera_params: CameraParameters) -> Tuple[float, float]:
+        pass
+    
+    @abstractmethod
+    def unproject(self, pixel: Tuple[float, float], depth: float, camera_params: CameraParameters) -> np.ndarray:
+        pass
+    
+    @abstractmethod
+    def get_focal_length(self, camera_params: CameraParameters) -> Tuple[float, float]:
+        pass
+    
+    @abstractmethod
+    def apply_distortion(self, pixel: Tuple[float, float], distortion_coeffs: List[float]) -> Tuple[float, float]:
+        pass
+    
+    @abstractmethod
+    def remove_distortion(self, pixel: Tuple[float, float], distortion_coeffs: List[float]) -> Tuple[float, float]:
+        pass
+```
+
+## Component Description
+
+Pinhole camera projection model with Brown-Conrady distortion handling.
+
+## API Methods
+
+### `project(point_3d: np.ndarray, camera_params: CameraParameters) -> Tuple[float, float]`
+
+**Description**: Projects 3D point to 2D image pixel.
+
+**Formula**:
+```
+x = fx * X/Z + cx
+y = fy * Y/Z + cy
+```
+
+---
+
+### `unproject(pixel: Tuple[float, float], depth: float, camera_params: CameraParameters) -> np.ndarray`
+
+**Description**: Unprojects pixel to 3D ray at given depth.
+
+**Formula**:
+```
+X = (x - cx) * depth / fx
+Y = (y - cy) * depth / fy
+Z = depth
+```
+
+---
+
+### `get_focal_length(camera_params: CameraParameters) -> Tuple[float, float]`
+
+**Description**: Returns (fx, fy) in pixels.
+
+**Formula**:
+```
+fx = focal_length_mm * image_width / sensor_width_mm
+fy = focal_length_mm * image_height / sensor_height_mm
+```
+
+---
+
+### `apply_distortion(pixel: Tuple[float, float], distortion_coeffs: List[float]) -> Tuple[float, float]`
+
+**Description**: Applies radial and tangential distortion (Brown-Conrady model).
+
+---
+
+### `remove_distortion(pixel: Tuple[float, float], distortion_coeffs: List[float]) -> Tuple[float, float]`
+
+**Description**: Removes distortion from observed pixel.
+
+## Dependencies
+
+**External**: opencv-python, numpy
+
+## Data Models
+
+```python
+class CameraParameters(BaseModel):
+    focal_length: float  # mm
+    sensor_width: float  # mm
+    sensor_height: float  # mm
+    resolution_width: int
+    resolution_height: int
+    principal_point: Tuple[float, float]  # (cx, cy) pixels
+    distortion_coefficients: List[float]  # [k1, k2, p1, p2, k3]
+```
+