feat: 波长偏移修正 + 项目架构文档

- BandMathCalculator 支持 wavelength_offset 参数，公式波长统一加减偏移后匹配传感器波段
- WaterQualityIndexCalculator 全链传递偏移量 (band_math → calculate_one → calculate_many)
- WaterIndexCsvProcessor / Step7Handler / DataPreparationStep 传播偏移参数
- Step7/Step10 面板新增 QDoubleSpinBox 波长偏移控件 (±200nm, 默认0)
- 偏移控件去除单位后缀，避免编辑时需手动移动光标
- 新增 ARCHITECTURE.md 完整项目架构文档

src/core/algorithms/waterindex_inversion/csv_processor.py

@@ -114,6 +114,7 @@ class WaterIndexCsvProcessor:
         output_dir: str,
         selected_formulas: Optional[List[str]] = None,
         progress_callback: Optional[Callable[[str, float], None]] = None,
+        wavelength_offset: float = 0.0,
     ) -> Dict[str, str]:
         """
         散点 CSV → 按指数拆分的多个 CSV。
@@ -128,6 +129,8 @@ class WaterIndexCsvProcessor:
             要计算的公式名列表；None 或空列表 = 全部公式
         progress_callback : callable, optional
             进度回调 ``(msg: str, pct: float)``
+        wavelength_offset : float
+            波长偏移修正量（nm），公式波长统一加上此值后再匹配波段
 
         Returns
         -------
@@ -192,7 +195,7 @@ class WaterIndexCsvProcessor:
         notify(f"开始逐行计算 {len(targets)} 个公式…", 25)
         spectra_df = df[wl_cols]
         try:
-            results_df = calc.calculate_many(targets, spectra_df)
+            results_df = calc.calculate_many(targets, spectra_df, wavelength_offset=wavelength_offset)
         except Exception as e:
             raise RuntimeError(f"公式计算失败: {e}")
 

src/core/handlers/step7_calc_indices.py

@@ -38,6 +38,7 @@ class Step7CalcIndicesHandler(BaseStepHandler):
                 output_file=config.get('output_file'),
                 enabled=config.get('enabled', True),
                 output_dir=str(context.indices_dir),
+                wavelength_offset=float(config.get('wavelength_offset', 0)),
             )
 
             context.indices_path = result

src/core/steps/data_preparation_step.py

@@ -133,6 +133,7 @@ class DataPreparationStep:
         enabled: bool = True,
         output_dir: Union[str, Path] = "./7_Water_Quality_Indices",
         callback: Optional[Callable] = None,
+        wavelength_offset: float = 0.0,
     ) -> Optional[str]:
         """根据训练光谱计算水质光谱指数（使用 band_math 方法）"""
         output_dir = Path(output_dir)
@@ -170,7 +171,7 @@ class DataPreparationStep:
 
         from src.utils.band_math import BandMathCalculator
 
-        calculator = BandMathCalculator(training_csv_path)
+        calculator = BandMathCalculator(training_csv_path, wavelength_offset=wavelength_offset)
         result_df = calculator.process_formulas_from_csv(
             formula_csv_file=formula_csv_file,
             formula_names=formula_names,