PINN: allinea output a results/pinn/ e centralizza parametri in config

- visualizer.py: sostituisce animations/ con results/pinn/TIMESTAMP/,
  nomi fissi (heatmap.html, animation.html, comparison.html) come FDM
- config.py: aggiunge sezioni architettura, sampling, Adam, L-BFGS, loss weights
- model.py: costruisce HeatPINN dinamicamente da HIDDEN_SIZE/N_HIDDEN_LAYERS;
  heat_pinn_loss legge pesi W_PDE/W_IC/W_BC da config
- engine.py: tutti i parametri di training letti da config

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

visualizer.py

@@ -1,15 +1,17 @@
 import os
+from datetime import datetime
 import numpy as np
 import plotly.graph_objects as go
 from plotly.subplots import make_subplots
 import config
 
 BASE_DIR = os.path.dirname(os.path.abspath(__file__))
-ANIMATIONS_DIR = os.path.join(BASE_DIR, 'animations')
 
 
 def visualize_heat_field(T_pred, x_vals, t_vals, T_fdm):
-    os.makedirs(ANIMATIONS_DIR, exist_ok=True)
+    timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
+    out_dir = os.path.join(BASE_DIR, 'results', 'pinn', timestamp)
+    os.makedirs(out_dir, exist_ok=True)
 
     # Downsample T_fdm from shape (NX_fdm, NT_fdm) to match PINN grid
     nx_pred = len(x_vals)
@@ -44,9 +46,9 @@ def visualize_heat_field(T_pred, x_vals, t_vals, T_fdm):
     fig_map.update_yaxes(title_text='t', row=1, col=1)
     fig_map.update_layout(title_text='Heat Equation PINN vs FDM', height=450)
 
-    map_path = _next_path('heatmap', '.html')
+    map_path = os.path.join(out_dir, 'heatmap.html')
     fig_map.write_html(map_path)
-    print(f"Heatmap saved → {map_path}")
+    print(f"Heatmap saved        → {map_path}")
 
     # --- Animated profile T(x) evolving in time ---
     n_frames = len(t_vals)
@@ -92,9 +94,9 @@ def visualize_heat_field(T_pred, x_vals, t_vals, T_fdm):
         frames=frames,
     )
 
-    anim_path = _next_path('heat_animation', '.html')
+    anim_path = os.path.join(out_dir, 'animation.html')
     fig_anim.write_html(anim_path)
-    print(f"Animation saved  → {anim_path}")
+    print(f"Animation saved      → {anim_path}")
 
     # --- Time-series comparison at fixed spatial points ---
     # Spatial indices for x=0, x=L/2, x=L
@@ -141,15 +143,6 @@ def visualize_heat_field(T_pred, x_vals, t_vals, T_fdm):
         height=500,
     )
 
-    comparison_path = _next_path('comparison', '.html')
+    comparison_path = os.path.join(out_dir, 'comparison.html')
     fig_ts.write_html(comparison_path)
-    print(f"Time-series saved → {comparison_path}")
-
-
-def _next_path(prefix, ext):
-    i = 1
-    while True:
-        path = os.path.join(ANIMATIONS_DIR, f'{prefix}_{i:03d}{ext}')
-        if not os.path.exists(path):
-            return path
-        i += 1
+    print(f"Comparison saved     → {comparison_path}")