When subscriptions through Paddle expire, there is no in-app notification

### Description

We have a user who has reported that they did not get any in-app notification when their subscription (through Paddle, instead of Google) expired. I'm pretty sure the in-app notification works fine when a subscription made through Google expires because I see it all the time when I'm testing, but it sounds like this doesn't happen when the subscription is through Paddle.

We should present a notification anytime a user's subscription status changes from paid to free.

### Step-by-step reproduction instructions

As reported by the user:
1. Create a subscription through Paddle
2. Log into that account on the Android app
3. Cancel the paddle subscription (note that in this case the user says they didn't actually cancel their subscription, but that's probably a separate issue)
4. Wait for the subscription to expire
5. Verify that the app does not present any notification that you are now a free user.

### Screenshots or screen recording

_No response_

### Did you search for existing bug reports?

- [X] I have searched for existing bug reports.

### Device, Operating system, and Pocket Casts app version

_No response_

Start by tracing how the Android app receives and applies Paddle subscription status changes, then compare that path with the Google expiration flow described in the issue. Reproduce the reported steps with a Paddle subscription and verify that a notification appears when the account changes from paid to free.

Written by the indexing model from the issue text.