feat: notification test endpoints — POST /api/push/test and /api/push/reminders/check

- POST /api/push/test: sends "Test notification from Cortex" via the
  user's configured notification channel (web_push / NCT / email / etc.)
- POST /api/push/reminders/check: runs the daily reminder check immediately
  for the current user, returns reminders_found count

Both require an active session cookie. Useful for verifying channel setup
without waiting for the 09:00 scheduler job.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/routers/push.py

@@ -58,3 +58,63 @@ async def unsubscribe(req: UnsubscribeRequest, request: Request) -> dict:
     username = _require_user(request)
     found = push_utils.remove_subscription(username, req.endpoint)
     return {"ok": True, "found": found}
+
+
+@router.post("/test")
+async def notify_test(request: Request) -> dict:
+    """Send a test notification via the user's configured notification channel.
+
+    Useful for verifying channel setup (web push, NCT, email, etc.) without
+    waiting for a cron job or reminder to fire naturally.
+    """
+    username = _require_user(request)
+    from notification import notify
+    await notify(username, "Test notification from Cortex — your notification channel is working.")
+    return {"ok": True, "user": username}
+
+
+@router.post("/reminders/check")
+async def reminder_check_now(request: Request) -> dict:
+    """Run the reminder check for the current user immediately.
+
+    Same logic as the daily 09:00 scheduler job, but scoped to one user
+    and fired on demand. Returns how many reminders were found and whether
+    a notification was sent.
+    """
+    import re
+    username = _require_user(request)
+
+    from persona import list_user_personas, set_context
+    from notification import notify
+
+    total_sent = 0
+    for persona_name in list_user_personas(username):
+        set_context(username, persona_name)
+        from tools.reminders import load_due_reminders
+        content = load_due_reminders()
+        if not content:
+            continue
+
+        entries = []
+        for line in content.splitlines():
+            m = re.match(r"^\d+\.\s+(.+)", line.strip())
+            if m:
+                text = re.sub(r"\[(OVERDUE|due TODAY|due: \S+)\]", "", m.group(1)).strip()
+                if text:
+                    entries.append(text)
+
+        if not entries:
+            continue
+
+        count = len(entries)
+        if count == 1:
+            msg = f"Reminder: {entries[0]}"
+        else:
+            bullet_list = "\n".join(f"• {e}" for e in entries[:3])
+            tail = f"\n…and {count - 3} more" if count > 3 else ""
+            msg = f"{count} reminders due:\n{bullet_list}{tail}"
+
+        await notify(username, msg)
+        total_sent += count
+
+    return {"ok": True, "user": username, "reminders_found": total_sent}