docs: describe the shipped SDK surface instead of the 2026-05 scaffold status

README still claimed generated bindings would land later and
Studio ran on mock data; CHANGELOG was the create-package stub.
Both now state the actual surface (full Hub+HubAdmin client,
streaming, detached invocations, gRPC + gRPC-Web, bearer auth)
and the path/git-dep distribution model.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

CHANGELOG.md

@@ -1,3 +1,24 @@
-## 1.0.0
+# Changelog
 
-- Initial version.
+The SDK version tracks the platform release that shipped the
+matching wire surface; see the platform repo's `CHANGELOG.md`
+for the authoritative per-release detail.
+
+## 0.18.x (current)
+
+- Full Hub + HubAdmin coverage: `submit` (incl. `detach:`),
+  `submitStreaming`, `runSavedFlow` (text/bytes/json inputs),
+  detached invocation status/result/cancel, saved flows, store +
+  module management, audit (`eventLog`, `streamEvents`,
+  `verifyEventChain`), approvals, federation admin
+  (`listSatellites`, `issueBootstrapToken`, `revokeSatellite`),
+  MCP/n8n endpoint management, System-AI administration.
+- Bearer-token auth via `HubClient(authToken:)`.
+- Native gRPC + gRPC-Web transports (conditional import).
+- Generated bindings for the renamed `chain.v1` wire package.
+
+## Earlier
+
+- 0.x line grew alongside the platform (package started as a
+  scaffold named `fai_client_sdk`, renamed to
+  `chain_client_sdk` in the product rename, 2026-06).