feat: set up release-plz for automated versioning and changelog (#74)

Configures release-plz to automate the release workflow:
- GitHub Action (.github/workflows/release-plz.yml) runs on push to main
- Analyzes conventional commits to determine version bumps
- Opens release PRs with version bump and changelog updates
- On merge: creates git tag, publishes to crates.io, triggers cargo-dist
- Runs cargo-semver-checks to catch breaking API changes

Also adds:
- release-plz.toml configuration (publish, changelog, semver checks)
- cliff.toml for git-cliff changelog generation with grouped sections
- CHANGELOG.md with initial unreleased features

Conventional commit format:
- feat: → minor bump, fix: → patch bump
- feat!: or BREAKING CHANGE: → major bump
- chore:, docs:, ci: → no bump

Fixes #68

Author: alvinreal

.github/workflows/release-plz.yml

@@ -0,0 +1,31 @@
+name: Release-plz
+
+permissions:
+  pull-requests: write
+  contents: write
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  release-plz:
+    name: Release-plz
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Run release-plz
+        uses: release-plz/action@v0.5
+        with:
+          command: release-pr
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}

CHANGELOG.md

@@ -0,0 +1,20 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Features
+
+- Universal data format converter with mapping language
+- Support for JSON, YAML, TOML, CSV, XML, MessagePack, JSON Lines formats
+- Mapping language with rename, select, drop, set, cast, where, each, when, flatten, nest, sort, default operations
+- 30+ built-in functions (string, math, collection, type operations)
+- Streaming mode for large files (JSONL, CSV, JSON array)
+- Shell completions for bash, zsh, fish, PowerShell, elvish
+- Error UX with "did you mean?" suggestions for formats and functions
+- Performance benchmark suite with Criterion
+- cargo-dist setup for automated release builds

cliff.toml

@@ -0,0 +1,51 @@
+# git-cliff configuration for changelog generation
+# https://git-cliff.org/docs/configuration
+
+[changelog]
+header = """
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+"""
+body = """
+{% if version -%}
+## [{{ version | trim_start_matches(pat="v") }}] - {{ timestamp | date(format="%Y-%m-%d") }}
+{% else -%}
+## [Unreleased]
+{% endif -%}
+
+{% for group, commits in commits | group_by(attribute="group") %}
+### {{ group | upper_first }}
+{% for commit in commits %}
+- {% if commit.breaking %}**BREAKING**: {% endif %}{{ commit.message | upper_first }} \
+  ([{{ commit.id | truncate(length=7, end="") }}](https://github.com/alvinreal/morph/commit/{{ commit.id }}))\
+{% endfor %}
+{% endfor %}
+"""
+trim = true
+
+[git]
+conventional_commits = true
+filter_unconventional = true
+split_commits = false
+protect_breaking_commits = true
+filter_commits = false
+tag_pattern = "v[0-9].*"
+sort_commits = "newest"
+
+commit_parsers = [
+    { message = "^feat", group = "Features" },
+    { message = "^fix", group = "Bug Fixes" },
+    { message = "^doc", group = "Documentation" },
+    { message = "^perf", group = "Performance" },
+    { message = "^refactor", group = "Refactor" },
+    { message = "^style", group = "Styling" },
+    { message = "^test", group = "Testing" },
+    { message = "^chore", group = "Miscellaneous" },
+    { message = "^ci", group = "CI/CD" },
+    { message = "^build", group = "Build" },
+]

release-plz.toml

@@ -0,0 +1,15 @@
+# release-plz configuration
+# https://release-plz.dev/docs/config
+
+[workspace]
+# Use git-cliff for changelog generation
+changelog_config = "cliff.toml"
+
+[[package]]
+name = "morph"
+# Publish to crates.io when the release PR is merged
+publish = true
+# Generate changelog
+changelog_update = true
+# Run semver checks to catch breaking changes
+semver_check = true