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>

cliff.toml

@@ -0,0 +1,45 @@
+[changelog]
+header = """
+# Changelog\n
+All notable changes to this project will be documented in this file.\n
+"""
+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 | striptags | trim | upper_first }}
+{% for commit in commits %}
+- {{ commit.message | upper_first }}\
+{% endfor %}
+{% endfor %}\n
+"""
+trim = true
+footer = ""
+
+[git]
+conventional_commits = false
+filter_unconventional = false
+split_commits = false
+commit_parsers = [
+  { message = "^[Ff]eat", group = "Features" },
+  { message = "^[Ff]ix", group = "Bug Fixes" },
+  { message = "^[Dd]oc", group = "Documentation" },
+  { message = "^[Pp]erf", group = "Performance" },
+  { message = "^[Rr]efactor", group = "Refactor" },
+  { message = "^[Ss]tyle", group = "Styling" },
+  { message = "^[Tt]est", group = "Testing" },
+  { message = "^[Cc]hore", group = "Miscellaneous Tasks" },
+  { message = "^[Aa]dd", group = "Features" },
+  { message = "^[Ee]nable", group = "Features" },
+  { message = "^[Rr]emove", group = "Changes" },
+  { message = ".*", group = "Changes" },
+]
+filter_commits = false
+tag_pattern = "v[0-9]*"
+skip_tags = ""
+ignore_tags = ""
+topo_order = false
+sort_commits = "oldest"