docs: seed CHANGELOG.md (Keep-a-Changelog format) (#217)

## Summary
Adds an initial `CHANGELOG.md` in Keep-a-Changelog format. Recent
commits are bucketed into Added/Fixed/Changed/Documentation/CI from
their conventional-commit prefixes.

Closes **Row-2 Phase 3** of the 2026-05-26 estate tech-debt audit chain
for this repo. The audit
([standards#197](#197))
flagged 180/279 repos missing CHANGELOG (65% gap).

## Adopting auto-regeneration
For ongoing auto-regeneration, adopt the
[`changelog-reusable.yml`](https://github.com/hyperpolymath/standards/blob/main/.github/workflows/changelog-reusable.yml)
workflow
([standards#206](#206))
in this repo's CI. Uses the canonical
[`templates/cliff.toml`](https://github.com/hyperpolymath/standards/blob/main/templates/cliff.toml).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

CHANGELOG.md

@@ -0,0 +1,74 @@
+<!--
+SPDX-License-Identifier: MPL-2.0
+SPDX-FileCopyrightText: 2026 Jonathan D.A. Jewell (hyperpolymath)
+-->
+
+# Changelog
+
+All notable changes to `standards` will be documented in this file.
+
+This file is generated from conventional commits by the
+[`changelog-reusable.yml`](https://github.com/hyperpolymath/standards/blob/main/.github/workflows/changelog-reusable.yml)
+workflow (`hyperpolymath/standards#206`). Adopt the workflow in this repo's CI to keep this file in sync automatically — see
+[`templates/cliff.toml`](https://github.com/hyperpolymath/standards/blob/main/templates/cliff.toml)
+for the canonical config.
+
+The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/);
+this project aims to follow [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+
+- feat(governance): add scorecard-reusable.yml — close 5-candidate convergence set (#205)
+- feat(changelog): add git-cliff config + reusable workflow (#206)
+- feat(cartridges): canonicalise BoJ cartridge format in standards/ (#200)
+- feat(governance): add secret-scanner-reusable.yml — propagate shell-secrets to 281 repos (#190)
+- feat(governance): add mirror-reusable.yml — consolidate 289-repo mirror.yml drift (#187)
+- feat(launcher-standard): reference impls for soft-attach + gui-dialog-chain (#179)
+- feat(launcher-standard): require --version mode with machine-greppable format (#173)
+- feat: consume .hypatia-baseline.json in governance gate (#166)
+
+### Fixed
+
+- fix(governance): eradicate inline Python from governance-reusable.yml (#189)
+- fix(launcher-standard): resolve 3 cross-doc contradictions (#170)
+- fix(baseline): file_pattern glob matching + jq scoping bugs (#180)
+- fix(launcher-standard): move PID/log to XDG dirs (security: symlink-attack hardening) (#175)
+- fix(keepopen): honour NO_COLOR and auto-strip ANSI for non-TTY stdout (#176)
+- fix: checkout caller's repo in governance-reusable workflow (#165)
+- fix: checkout caller's repo in governance-reusable workflow
+- fix: use canonical STATE completion field
+- fix(security): enforce SSH-only git remotes estate-wide (standards#69) (#147)
+- fix(licence): #3 isolated — clear scaffold-placeholder leak (standards) (#139)
+
+### Changed
+
+- refactor(governance): subsume language-policy.yml + add deno-ci-reusable (semantics-level fix for estate-template drift) (#168)
+
+### Documentation
+
+- docs(policies): trusted-base reduction policy for proof debt (#203)
+- docs: launcher-standard review 2026-05-26 — prose + a2ml campaign manifest (#182)
+- docs(audits): admin-merge wrapper sweep 2026-05-26 (human + a2ml) (#202)
+- docs: exempt palimpsest plasma licensing repo
+- docs: add scaffold-stub guix.scm debt tracker (Refs standards#102)
+- docs(nix-retirement): closure report + machine-readable record (#102 #103) (#149)
+- docs(licence-policy): restore A6+A7 dropped by #143/#144 merge race (#146)
+- docs(licence-policy): A8 — explicit owner-sanctioned scoped carve-outs (#144)
+- docs(licence-policy): A6 hard-exclusions + A7 multi-SPDX FP ignore-list (ledger #2/#3) (#143)
+- docs(licence-policy): A5 — scaffold-placeholder leak is NOT licence debt (#140)
+
+### CI
+
+- ci: add launcher-standard prose↔a2ml lock-step gate (#172)
+- ci(tooling): promote standards R4 lint to strict (#159)
+- ci(spark): SPARK Theatre Gate reusable workflow (#135) (#141)
+
+## Pre-history
+
+Prior commits to this file's introduction are recorded in git history but not formally classified into Keep-a-Changelog sections. To backfill, run `git cliff -o CHANGELOG.md` locally using the canonical [`cliff.toml`](https://github.com/hyperpolymath/standards/blob/main/templates/cliff.toml) — this is one-shot mechanical work.
+
+---
+
+<!-- This file was seeded by the 2026-05-26 estate tech-debt audit follow-up (Row-2 Phase 3); see [`hyperpolymath/standards/docs/audits/2026-05-26-estate-documentation-debt.md`](https://github.com/hyperpolymath/standards/blob/main/docs/audits/2026-05-26-estate-documentation-debt.md). -->