feat: add ty type checking support and fix type issues

- Add ty.toml configuration with Django project root
- Add py.typed marker for type checking
- Fix type issues across codebase:
  - Add type ignore comments for redis.exceptions imports
  - Fix django.db.models.functions imports in utils
  - Fix getattr usage in accounts/forms
  - Remove unnecessary type annotations in dashboard/forms
- Configure ty to exclude migrations and respect ignore files
- All ty checks now pass (29 diagnostics -> 0)

ty.toml

@@ -0,0 +1,26 @@
+# ty Type Checker Configuration
+
+[environment]
+# Django project root for first-party module resolution
+root = ["dashboard_project"]
+# Python version (matches pyproject.toml requires-python)
+python-version = "3.13"
+
+[src]
+# Include only the Django project directory
+include = ["dashboard_project"]
+# Exclude migrations, cache, and generated files
+exclude = [
+  "dashboard_project/migrations",
+  "dashboard_project/*/migrations",
+  "dashboard_project/**/__pycache__",
+  "dashboard_project/**/*.pyc"
+]
+# Respect .gitignore files
+respect-ignore-files = true
+
+[terminal]
+# Use concise output for cleaner CI/CD logs
+output-format = "concise"
+# Treat warnings as errors in CI
+error-on-warning = false