docs: seed CHANGELOG.md (Keep-a-Changelog format) (#35)

Closes Row-2 Phase 3 of the 2026-05-26 estate tech-debt audit chain
for this repo. The 2026-05-26 documentation-debt audit
(hyperpolymath/standards#197) flagged that 180 of 279 estate repos
lacked a CHANGELOG.md (65% gap) — this seed closes that finding here.

The seed:
  - Uses Keep-a-Changelog format with an [Unreleased] section.
  - Buckets the most recent 100 commits by conventional-commit prefix
    (feat/fix/refactor/docs/ci/build) into Added/Fixed/Changed/
    Documentation/CI sections.
  - References standards#206's changelog-reusable.yml + the canonical
    templates/cliff.toml for full-regeneration via git-cliff.

The file is initial — the maintainer can adopt changelog-reusable.yml
in this repo's CI to keep it auto-regenerated, or regenerate manually.

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

Author: hyperpolymath

CHANGELOG.md

@@ -0,0 +1,46 @@
+<!--
+SPDX-License-Identifier: MPL-2.0
+SPDX-FileCopyrightText: 2026 Jonathan D.A. Jewell (hyperpolymath)
+-->
+
+# Changelog
+
+All notable changes to `claude-gecko-browser-extension` 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]
+
+### Fixed
+
+- fix(examples): migrate SafeDOMExample.affine to current AffineScript grammar (Refs gitbot-fleet#148, #208) (#30)
+- fix(licence): gecko MPL-2.0 throughout (owner-ruled, full repo) (#24)
+- fix(licence): gecko scaffold/variant -> MPL-2.0 (owner-ruled) (#23)
+- fix(ci): sync hypatia-scan.yml to canonical (413: env.HOME+Phase-2+SARIF) (#18)
+- fix(ci): adopt canonical hypatia-scan.yml (env.HOME/scanner-layout + Comment-step gate) (#16)
+- fix(ci): rsr-antipattern.yml duplicate heredoc (#15)
+- fix: remove duplicate SCM files from root
+- fix(security): update editorconfig SHA and CodeQL language
+
+### CI
+
+- ci(secret-scanner): drop duplicate --fail from trufflehog extra_args (#14)
+- ci: fix workflow-linter YAML parse error + self-flag bug
+- ci: fix workflow-linter self-flag bug
+- ci(antipattern): fix top-level dir matching + benchmarks/lsp/bench filename allowlists (#10)
+- ci(antipattern): TS check reads .claude/CLAUDE.md exemption table (#9)
+
+## 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). -->