feat(memory): add opt-in scoped memory tools

CHANGELOG.md

@@ -2,6 +2,16 @@
 
 All notable changes to this project are documented here.
 
+## [Unreleased]
+
+### Added
+- Add opt-in session and project memory tools backed by OpenCode plugin storage,
+  with explicit retrieval, deletion, project/session isolation, and expiry.
+
+### Documentation
+- Document memory opt-in, scope, retention, storage limitations, and uninstall
+  behavior for plugin entries with user options.
+
 ## [0.1.0-rc.1] - 2026-10-08
 
 ### Distribution