chore(release): MIT license + CONTRIBUTING/SECURITY/CODE_OF_CONDUCT + README badges (S12)

CHANGELOG.md

@@ -1,3 +1,19 @@
 # Changelog
 
 All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+- Sibling implementation of the portfolio-optimiser method on the Claude Agent SDK (D7),
+  built from the shared frozen spec + golden suite alone.
+- Deterministic backbone (mandatory blocking validator), the agentic + learning loop
+  (S5–S10), and the deterministic ingest layer (CSV + SQL source types), each wired seam by
+  seam and proven by load-bearing tests.
+- Test suite: 265 passing tests, all running offline without an API key.
+
+### Notes
+- Licensed under the MIT License (see `LICENSE`).