v0.8.9: Format email timestamps as 'Tuesday, August 8, 2026 @ 9:24pm' in America/Regina timezone

Add regina_dt Jinja2 template filter that converts UTC ISO-8601 timestamps
to America/Regina timezone and formats them as 'Weekday, Month D, YYYY @ H:MMam/pm'.
Applied to preview_sent_at and delivery_sent_at on the admin request page.

app.py

@@ -91,6 +91,25 @@ from helpers import (
 app = Flask(__name__)
 app.config.from_object(Config)
 
+# Template filter: format UTC ISO timestamp as "Tuesday, August 8, 2026 @ 9:24pm" in America/Regina.
+from datetime import datetime, timezone
+from zoneinfo import ZoneInfo
+
+_REGINA_TZ = ZoneInfo("America/Regina")
+
+@app.template_filter("regina_dt")
+def regina_dt_filter(value):
+    if not value:
+        return ""
+    try:
+        dt = datetime.fromisoformat(value)
+        if dt.tzinfo is None:
+            dt = dt.replace(tzinfo=timezone.utc)
+        dt = dt.astimezone(_REGINA_TZ)
+        return dt.strftime("%A, %B %-d, %Y @ %-I:%M%p").replace("AM", "am").replace("PM", "pm")
+    except (ValueError, TypeError):
+        return value
+
 # Global request rate limiting by remote IP (default 60/min). The public form is further limited to 5/min.
 limiter = Limiter(get_remote_address, app=app, default_limits=["60 per minute"])