Notification API: In-app delivery only (no push/badge)

Description

Path: /apps/technical-guides/base-notifications

## Problem

Notifications sent via `/api/v1/notifications/send` only show up in the in-app notification center. They don't trigger push notifications, lock screen alerts, or badge indicators.

This means users have no idea they received a notification unless they manually open the notifications panel.

## What happens now

**API notifications:**
- Show in notification center ✓
- Push to lock screen ✗
- Badge on notification icon ✗

**On-chain notifications (token transfers, etc.):**
- Show in notification center ✓
- Push to lock screen ✓
- Badge on notification icon ✓

## Why this matters

We tested with multiple users - none of them noticed the notifications until we told them to check. They just don't see them.

This defeats the purpose of notifications. Users need to be alerted about time-sensitive things like rewards expiring, events ending, or getting outbid. Right now the notification API is basically useless for user retention.

## Suggested fix

Make API notifications behave the same as on-chain notifications - deliver them as actual push notifications that users will see.