docs: add CHANGELOG for v0.1.0 release

Author: introfini

CHANGELOG.md

@@ -0,0 +1,14 @@
+# Changelog
+
+## [0.1.0] - 2026-03-13
+
+### Initial Release
+
+- **17 resource groups**: contacts, segments, emails, campaigns, forms, companies,
+  notes, stages, assets, tags, categories, pages, webhooks, fields, reports, points
+- **65 commands** covering list, get, create, edit, delete, and resource-specific actions
+- **Output formats**: JSON (default), table (Rich), CSV, NDJSON (auto-paginating)
+- **Auth**: Basic Auth and OAuth2 Client Credentials with named profiles
+- **Global flags**: --format, --page-all, --published-only, --dry-run, --verbose, --no-verify-ssl
+- **AI agent skill**: installable via `npx skills add bloomidea/mautic-cli`
+- Mautic 4.x through 7.x supported