docs: seed CHANGELOG.md (Keep-a-Changelog format) (#218)

## 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](hyperpolymath/standards#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](hyperpolymath/standards#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 +1,61 @@
+<!--
+SPDX-License-Identifier: MPL-2.0
+SPDX-FileCopyrightText: 2026 Jonathan D.A. Jewell (hyperpolymath)
+-->
+
+# Changelog
+
+All notable changes to `gitbot-fleet` 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(sustainabot): migrate bot-integration from ReScript to AffineScr… (#199)
+- feat(scripts): add fix-tracked-package-lock.sh for standards#67 enforcement (#170)
+- feat(robot-repo-automaton): canonical RSR skeleton generator (rsr-template-repo#48) (#160)
+- feat(rhodibot): add offline `check` CLI subcommand for CI gating (#150)
+- feat(gsbot)!: faithful Rust/SPARK port — eliminate Python from the fleet (#145)
+
+### Fixed
+
+- fix(examples): migrate SafeDOMExample.affine to current AffineScript grammar (closes #208) (#210)
+- fix(sustainabot): parse-blocking OCaml-isms and HANDLE-keyword name (Refs #148) (#206)
+- fix(licence): clear scaffold-placeholder leak (isolated; dirty repo) (#167)
+- fix(ci): pin upload-artifact to valid SHA in fix-unpinned-actions.sh generator (Refs standards#48) (#163)
+- fix(ci): bump a2ml/k9-validate-action pins to canonical (standards#85) (#162)
+- fix(ci): sync hypatia-scan.yml to canonical (kill cd-scanner build drift) (#161)
+- fix: resolve gitbot-fleet legacy hypatia findings at source; de-baseline (#152)
+- fix(ci): adopt canonical hypatia-scan.yml (env.HOME/scanner-layout + Comment-step gate) (#151)
+- fix(shared-context): clear pre-existing clippy -D warnings debt (item B) (#149)
+- fix: stagger estate push to stop CI thundering-herd (#147)
+
+### Documentation
+
+- docs(archive): session record for sustainabot #148 hand-port validation (#209)
+- docs: promote stub .adoc to faithful AsciiDoc from canonical .md (Item 11 Group A) (#159)
+
+### CI
+
+- ci: redistribute concurrency-cancel guard to read-only check workflows (#165)
+- ci(hypatia-scan): restore hardened workflow (supersedes #129) (#142)
+- ci(workflow): adopt hardened hypatia-scan from hyperpolymath/hypatia#237 (#126)
+- ci: bump actions/upload-artifact SHA to current v4 (#123)
+- ci(hypatia-scan): wire FLEET_DISPATCH_TOKEN to its own secret
+
+## 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). -->