update chicken weight to have chicken_area data as well

backend/database/ERD_Dashboard_Chicken_Counting.md

@@ -175,12 +175,7 @@ erDiagram
         int chicken_count "NOT NULL (n_weight_samples)"
         float uniformity "NOT NULL (Flock weight uniformity %)"
         float average_daily_gain "NOT NULL (ADG in grams/day)"
-        float area_cm2_median "Median body area in cm^2"
-        float minor_axis_cm_median "Median minor axis / width in cm"
-        float major_axis_cm_median "Median major axis / length in cm"
-        float gompertz_baseline_g "Theoretical Gompertz curve baseline"
-        float vision_gain_g "Allometric vision gain residual"
-        float rejection_rate "MAD outlier filter rejection percentage"
+        float chicken_area "NOT NULL DEFAULT 0.0 (Median chicken area in cm^2)"
         timestamp created_at "NOT NULL"
         timestamp updated_at "NOT NULL"
     }
@@ -308,8 +303,7 @@ Our edge pipeline aggregates floor camera runs and pushes clean daily rollups di
    - `chicken_count` $\leftarrow \sum \text{n\_weight\_samples}$ (valid non-outlier tracks).
    - `uniformity` $\leftarrow \text{flock size uniformity percentage}$.
    - `average_daily_gain` $\leftarrow \text{daily weight gain in grams/day}$.
-   - `area_cm2_median`, `minor_axis_cm_median`, `major_axis_cm_median` $\leftarrow \text{calibrated physical dimensions}$.
-   - `gompertz_baseline_g`, `vision_gain_g` $\leftarrow \text{audited growth model residual breakdown}$.
+   - `chicken_area` $\leftarrow \text{calibrated median chicken body area in cm²}$.
 
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