Bump to 0.9.1 and record the toolchain update

CHANGELOG.md

@@ -4,6 +4,16 @@ All notable user-facing changes to Gig Line. The format follows
 [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and versions use
 Semantic Versioning.
 
+## [0.9.1] — 2026-11-02
+
+### Changed
+
+- Unified the project, local tooling and CI/release environment on Godot 4.7.2,
+  including matching export templates and project feature metadata.
+- Added Gitea Actions cache for the Godot binary and export templates to reduce
+  repeated download time.
+- Updated release and setup documentation for the 4.7.2 baseline.
+
 ## [0.9.0] — 2026-11-01
 
 ### Added