feat(src): replace config with Django settings and add board view with context processors for dashboard metrics

Replace decouple config calls for Google OAuth credentials with settings; add new board view and associated context processors to render project board and dashboard charts; update serializer import path; centralize configuration and improve maintainability.

src/notes/serializers.py

@@ -1,4 +1,4 @@
-from apps.accounts.serializers import UserSerializer
+from src.accounts.serializers import UserSerializer
 from rest_framework import serializers
 
 from src.notes.models import ProjectNote