docs(changeset): add release notes

Author: gkoos

.changeset/hungry-points-knock.md

@@ -0,0 +1,16 @@
+---
+'@gkoos/ffetch': minor
+---
+
+Added
+
+- fetchHandler option to support pluggable/custom fetch implementations (SSR, edge, frameworks, polyfills).
+
+Changed
+
+- Removed manual AbortSignal combination fallback; AbortSignal.any is now required (native or polyfill).
+- Removed tests and code paths relying on the old signal combination fallback.
+
+Docs
+
+- Updated documentation to clarify AbortSignal.any requirement and polyfill instructions.