Update changelogs from fern repo (#4293)

Co-authored-by: amckinney <5760684+amckinney@users.noreply.github.com>

Author: fern-support

fern/products/cli-api-reference/cli-changelog/2026-03-13.mdx

@@ -1,3 +1,14 @@
+## 4.30.0
+**`(feat):`** Configures the `flatten_oneofs` configuration option for protoc-gen-openapi.
+When `flatten_oneofs` is enabled, the generated OpenAPI schema will flatten
+oneOf structures with a single schema. No additional configuration is required
+by the user.
+
+
+**`(fix):`** Add the `respectByteFormat` configuration option, which is implicitly enabled
+for gRPC/Protobuf specs.
+
+
 ## 4.29.0
 **`(feat):`** Add AI changelog rollup for multi-chunk diff analysis. When large diffs
 are split into multiple chunks, the resulting changelog entries are now

fern/products/sdks/overview/csharp/changelog/2026-03-13.mdx

@@ -1,3 +1,11 @@
+## 2.31.0
+**`(feat):`** Add support for `base64` primitive type in the IR to represent Protobuf byte[].
+
+
+**`(fix):`** Fix the `.ToProto` and `.FromProto` mapper methods to support for enums nested within
+message descriptors.
+
+
 ## 2.30.3
 **`(fix):`** Add better support for the `google.rpc.Status` type, and stop
 generating redundant wrapper types for `google.api` and