Add changelog service and release-new skill

- cliff.toml: git-cliff config with semantic-style grouping (no conventional commits required)
- CHANGELOG.md: initial changelog generated from full git history
- .claude/commands/release-new.md: /release-new [major|minor|patch] skill that bumps version, updates changelog, commits, tags, and pushes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/commands/release-new.md

@@ -0,0 +1,41 @@
+---
+allowed-tools: Bash(git tag:*), Bash(git add:*), Bash(git commit:*), Bash(git push:*), Bash(git log:*), Bash(git describe:*), Bash(git-cliff:*), Bash(git cliff:*)
+description: Create a new semver release. Usage: /release-new [major|minor|patch]
+---
+
+## Context
+
+- Current latest tag: !`git describe --tags --abbrev=0 2>/dev/null || echo "none"`
+- Current branch: !`git branch --show-current`
+- Unreleased commits: !`git log $(git describe --tags --abbrev=0 2>/dev/null || echo "")..HEAD --oneline 2>/dev/null || git log --oneline`
+
+## Your task
+
+Arguments: $ARGUMENTS (should be "major", "minor", or "patch")
+
+1. **Determine next version**:
+   - Get current latest tag (from context above). If none, start at v0.1.0.
+   - Parse the version as vMAJOR.MINOR.PATCH.
+   - Bump the appropriate component based on arguments (default: patch if none given).
+   - New version = vX.Y.Z (with "v" prefix).
+
+2. **Update CHANGELOG.md** using git-cliff:
+   ```
+   git-cliff --config cliff.toml --tag NEW_VERSION -o CHANGELOG.md
+   ```
+
+3. **Commit the changelog**:
+   - Stage: `git add CHANGELOG.md`
+   - Commit: `git commit -m "chore: release NEW_VERSION"`
+
+4. **Create annotated tag**:
+   ```
+   git tag -a NEW_VERSION -m "Release NEW_VERSION"
+   ```
+
+5. **Push commit and tag**:
+   ```
+   git push && git push --tags
+   ```
+
+Do not ask for confirmation. Execute all steps in sequence. Report what version was released when done.