Fix: efficient log reading (last 5000 chars only)

app.py

@@ -298,7 +298,12 @@ def _tokens_to_color(token_ids, grid_h=8, grid_w=8):
 def get_log():
     try:
         with open(LOG_FILE, "r") as f:
-            return f.read()
+            # Only read the last 5000 chars for efficiency
+            f.seek(0, 2)  # seek to end
+            size = f.tell()
+            f.seek(max(0, size - 5000))
+            content = f.read()
+            return content
     except:
         return "No pipeline log yet."