Release v2.2.0

- Add native Zulip notification support via zulip:// shoutrrr URLs (#271)
- Add ?messagekey= option for generic webhooks to rename the JSON payload
  field (#271)
- Change DELETE_ON_FAILURE default to false: preserve existing DNS records
  and skip WAF list updates when IP detection fails (#277)
- Document the local.iface.stable IPv6 provider and Helm chart added since
  v2.1.2

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

RELEASE_NOTES_2.2.0.md

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+# cloudflare-ddns v2.2.0 — Zulip Notifications, Safer Failure Handling & Helm Chart
+
+This minor release adds new notification and deployment options, a safer
+default when IP detection fails, and a stable IPv6 provider for Linux hosts.
+
+## ⚠️ Behavior change: `DELETE_ON_FAILURE` now defaults to `false` (#277)
+
+Previously, when a provider definitively reported no address for an IP
+family, managed DNS records for that family were **deleted** by default —
+which could take services offline after a transient misdetection.
+
+- `DELETE_ON_FAILURE` now defaults to **`false`**: on detection failure the
+  update is skipped and existing records are preserved.
+- Transient detection errors (network failures) always preserve existing
+  records, regardless of this setting.
+- WAF list updates are now skipped when any configured IP family fails
+  detection, preventing a partial failure from silently stripping that
+  family's IPs from the list.
+
+If you relied on the old behavior, set `DELETE_ON_FAILURE=true` explicitly.
+
+## New features
+
+- **Zulip notifications (#271).**
+  Native `zulip://` shoutrrr URL support:
+
+  ```text
+  zulip://bot-mail:bot-key@host/?stream=stream-name&topic=topic-name
+  ```
+
+  Messages are sent to the Zulip API (`/api/v1/messages`) with Basic auth.
+  The `@` in the bot email may be written literally or percent-encoded
+  (`%40`); `topic` is optional and defaults to `Cloudflare DDNS`.
+
+- **Configurable JSON field for generic webhooks (#271).**
+  Generic webhooks send `{"message": "..."}` by default. Append
+  `?messagekey=<field>` to rename the field — e.g.
+  `generic://host/path?messagekey=text` for services expecting Slack-style
+  payloads (including Zulip's slack-compatible endpoints).
+
+- **Stable local IPv6 provider (#273).**
+  New `local.iface.stable:<name>` provider selects the preferred stable
+  IPv6 address from a Linux network interface, excluding temporary
+  (privacy-extension) and deprecated addresses.
+
+- **Helm chart (#278).**
+  A Helm chart is now available under `charts/cloudflare-ddns`, published
+  as an OCI artifact to GHCR via CI.
+
+## Dependency updates
+
+- reqwest 0.13.4, rustls 0.23.42, tokio 1.52.4, rand 0.10.2,
+  serde_json 1.0.150, actions/checkout 7
+
+## Upgrade
+
+```bash
+docker pull timothyjmiller/cloudflare-ddns:2.2.0
+# or
+docker pull timothyjmiller/cloudflare-ddns:latest
+```
+
+No configuration changes are required unless you depend on records being
+deleted when IP detection fails — in that case set `DELETE_ON_FAILURE=true`.