Add tweak screenshots to README and Getting Started guide

Embeds four screenshots (committed under images/) from the upstream
tweak PR Apollo-Reborn/Apollo-Reborn#229:
- IMG_4296: Custom API > Notification Backend settings (README tweak
  section + guide step 6)
- IMG_4293: registration 'hello, is this thing on?' confirmation
  (guide step 6)
- IMG_4294 / IMG_4295: example PM and post-reply push notifications
  (guide step 7)

Author: nickclyde

GETTING_STARTED.md

@@ -331,6 +331,11 @@ On your iPhone, in Apollo (with the tweak installed):
 3. Tap **Test Connection**. This hits `GET /v1/health` on your backend — a success here means the
    app can reach it.
 
+<p align="center">
+  <img src="images/IMG_4296.jpg" width="300"
+       alt="Apollo Settings → Custom API → Notification Backend, with the Backend URL and Registration Token fields and a Test Connection button">
+</p>
+
 While you're here, double-check the **main Custom API screen** has your **Reddit API Key**,
 **Redirect URI**, and **User Agent** filled in for *this* bundle ID (you needed these to get Reddit
 browsing working at all). The notification backend reuses them.
@@ -341,6 +346,14 @@ Finally, **turn notifications on**:
 - Inside Apollo, enable inbox notifications for your account (and add any subreddit/user **watchers**
   you want).
 
+Once registration succeeds, the backend sends a **"hello, is this thing on?"** confirmation — a quick
+sign the whole chain is wired up:
+
+<p align="center">
+  <img src="images/IMG_4293.PNG" width="300"
+       alt="Apollo's in-app notifications settings showing the backend's 'hello, is this thing on?' confirmation after a successful registration">
+</p>
+
 ---
 
 ## 7. Verify end-to-end (a real push)
@@ -385,6 +398,16 @@ can swap in for `post_reply`:
 comment_reply   private_message   username_mention   subreddit_watcher   trending_post
 ```
 
+Here's what a delivered push looks like on the lock screen — a private message and a post reply:
+
+<p align="center">
+  <img src="images/IMG_4294.PNG" width="270"
+       alt="Private message push notification on the iOS lock screen">
+  &nbsp;
+  <img src="images/IMG_4295.PNG" width="270"
+       alt="Post reply push notification on the iOS lock screen">
+</p>
+
 ### 7c. The first-message "warmup" gotcha
 
 The **first real inbox message after registration won't notify you.** On its first poll the worker

README.md

@@ -104,6 +104,11 @@ In the tweak (Apollo on-device): **Settings > Custom API > Notification Backend*
 
 Tap **Test Connection** to verify the tweak can reach `GET /v1/health`.
 
+<p align="center">
+  <img src="images/IMG_4296.jpg" width="300"
+       alt="Apollo Settings > Custom API > Notification Backend, showing the Backend URL and Registration Token fields and the Test Connection button">
+</p>
+
 Make sure the **Reddit API Key**, **Redirect URI**, and **User Agent** in the tweak's main Custom API screen are filled in for the bundle ID you signed with — Reddit's API rules want a UA shaped like `ios:com.you.Leto:v1.0 (by /u/yourname)`. The tweak attempts to inject these into registration bodies; if injection fails, the backend falls back to the matching `REDDIT_*` env vars (see above). Either path works.
 
 Installed-app Reddit credentials are accepted — just leave the **Reddit API Secret** field blank in the tweak.