notifier: emit Apprise-compatible body/title in webhook payload

[nathang21]

Problem

Webhook notifications can't reach an Apprise instance. Apprise's REST API requires a body field and rejects any payload without one:

HTTP 400 {"error": "Payload lacks minimum requirements"}

Bindery's payloads only carry event-specific keys (title, message, size, …) and never a body, so every POST to an Apprise /notify/<key> endpoint fails — even with BINDERY_NOTIFICATIONS_ALLOW_PRIVATE=1 set (this is separate from #870; the request does reach Apprise, it's just rejected on shape).

Reproduce

# Bindery's test payload → rejected
curl -X POST -H 'Content-Type: application/json' \
  -d '{"eventType":"test","message":"Bindery notification test"}' \
  http://apprise:8000/notify/<key>
# → HTTP 400 {"error": "Payload lacks minimum requirements"}

# Same payload + a "body" → accepted, notification delivered
curl -X POST -H 'Content-Type: application/json' \
  -d '{"eventType":"test","message":"Bindery notification test","title":"Bindery","body":"Bindery notification test"}' \
  http://apprise:8000/notify/<key>
# → HTTP 200

Apprise ignores the extra eventType/message keys, confirming the fix can be purely additive.

Change

In notifier.send(), enrich a copy of the payload before marshaling:

• add body when absent — from message, falling back to title (covers grab/import which carry title, and test/health/failure which carry message);
• default title to "Bindery" when absent.

This is additive — the original keys are preserved, so ntfy / Home Assistant / Discord-proxy consumers are unaffected. A copy is used because Send reuses one payload map across every configured notification.

Tests

TestSend_AppriseFields covers the three cases (title-only, message-only, explicit-body-preserved) and asserts the caller's original keys survive untouched. Existing notifier tests still pass.

If you'd prefer to gate this on a notification "type" (e.g. type == "apprise") rather than always emitting body/title, happy to adjust.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!