Publish a changelog and adopt a consistent release template

[morcen]

Summary

Publish a changelog and adopt a consistent release template so Laravel Omni has a clear release history and repeatable release notes as it moves toward 1.0.

Why

The repository does not currently have a changelog or an obvious release-note template. That is manageable very early on, but it will get harder to reconstruct history once the package starts shipping regular milestones.

A small amount of release process now will make later releases easier to publish and easier for users to trust.

Current State

Observed gaps:

• no CHANGELOG.md in the repository
• no documented release-note template in the repo
• no tagged releases visible locally yet
• the roadmap now proposes a steady pre-1.0 release cadence

Proposed Scope

Changelog

• add a CHANGELOG.md
• choose a structure, for example Keep a Changelog style or a simpler semver-oriented format
• include an Unreleased section
• document how new entries should be added for future changes

Release template

• add a reusable release template for GitHub releases
• define the core sections for each release, such as:
  • highlights
  • added
  • changed
  • fixed
  • breaking changes or upgrade notes
  • testing/compatibility notes
• make sure the template works for both pre-1.0 and future stable releases

Process

• document a lightweight release workflow for maintainers
• decide whether changelog entries are updated per PR or during release prep
• align the release notes format with the roadmap milestones and semver expectations

Acceptance Criteria

• the repository contains a changelog with an Unreleased section
• the repository contains a release template maintainers can reuse
• there is a short documented process for keeping releases consistent
• future milestone releases can be published without inventing the format each time

Nice To Have

• seed the changelog with an initial entry describing the package's current baseline
• add a short release checklist to reduce missed steps during publishing