chore(push): release gateway chart 0.3.3 (#8107)

Prepares publication of the Buzz push gateway chart 0.3.3, including the
optional migration Pod annotations already merged in #8105. This PR adds
release notes only; chart templates, values, and schema are unchanged
from the reviewed implementation.

Merging the `push-chart-release/0.3.3` branch triggers the normal
release workflow: create `push-chart-v0.3.3`, validate the chart, then
publish `oci://ghcr.io/block/buzz/charts/buzz-push-gateway:0.3.3`. Keep
this PR in draft until publication is explicitly authorized. It does not
deploy a gateway.

### Validation

Focused migration annotation renders, release contract checks, and local
chart packaging pass. The merged implementation passed chart CI and
Jude's automated review in #8105. The earlier repository-wide local
`just ci` run failed in unchanged ACP tests; it was not rerun for
release notes. The registry manifest digest can only be verified after
publication.

---------

Signed-off-by: Tom Brow <tomb@block.xyz>

deploy/charts/buzz-push-gateway/CHANGELOG.md

@@ -0,0 +1,18 @@
+# Chart release notes
+
+## 0.3.3
+
+`gatewayOrigin` is now only an HTTPRoute routing input. It is optional unless
+`httpRoute.enabled=true`, and is no longer passed to the gateway container as
+`BUZZ_PUSH_GATEWAY_ORIGIN`. Implemented in
+[#7877](https://github.com/block/buzz/pull/7877).
+
+Adds optional `migration.podAnnotations` for the migration Job's Pod template.
+The default is empty. Annotation values must be strings, and migration Pod
+annotations are independent of runtime Deployment Pod annotations and Job hook
+metadata.
+
+For example, operators can set `migration.podAnnotations.sidecar.istio.io/inject`
+to the string `"false"` to opt migration Pods out of Istio sidecar injection.
+
+Implemented in [#8105](https://github.com/block/buzz/pull/8105).