fix: handle evtId zero when grouping grade components

Agent-Logs-Url: https://github.com/gablilli/chemediaho/sessions/811b0b06-3415-408a-ac20-267be06b3b1a

Co-authored-by: gablilli <167802854+gablilli@users.noreply.github.com>

Author: Copilot

app.py

@@ -1360,7 +1360,7 @@ def _get_effective_grades(grades_list):
         if g.get('componentDesc'):
             evt_id = g.get('evtId')
             key = evt_id if evt_id is not None else g.get('evtDate')
-            if key:
+            if key is not None and key != "":
                 if key not in component_groups:
                     component_groups[key] = []
                 component_groups[key].append(g['decimalValue'])