ci: add automated version bump, tag, and release script

Add scripts/release.sh that infers bump type from conventional commits
(major/minor/patch), bumps package.json, commits, tags, and pushes.
Includes safety checks for branch, clean tree, and remote sync.

Also adds a workflow_dispatch GitHub Actions workflow (bump.yml) and
Makefile targets (release, release-patch, release-minor, release-major).

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

scripts/release.sh

@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Automate version bump, tag, and push based on conventional commits.
+# Usage: bash scripts/release.sh [patch|minor|major]
+# If no argument is given, the bump type is inferred from commits since the last tag.
+
+BUMP="${1:-}"
+
+# --- Safety checks ---
+
+BRANCH=$(git rev-parse --abbrev-ref HEAD)
+if [[ "$BRANCH" != "main" ]]; then
+  echo "Error: must be on the main branch (currently on '$BRANCH')" >&2
+  exit 1
+fi
+
+if [[ -n "$(git status --porcelain)" ]]; then
+  echo "Error: working tree is not clean" >&2
+  exit 1
+fi
+
+git fetch origin main --tags --quiet
+LOCAL=$(git rev-parse HEAD)
+REMOTE=$(git rev-parse origin/main)
+if [[ "$LOCAL" != "$REMOTE" ]]; then
+  echo "Error: local main is not in sync with origin/main" >&2
+  echo "  local:  $LOCAL" >&2
+  echo "  remote: $REMOTE" >&2
+  exit 1
+fi
+
+# --- Bump type inference ---
+
+if [[ -z "$BUMP" ]]; then
+  LAST_TAG=$(git describe --tags --abbrev=0 --match 'v*' 2>/dev/null || echo "")
+  if [[ -z "$LAST_TAG" ]]; then
+    echo "No previous v* tag found, defaulting to patch"
+    BUMP="patch"
+  else
+    COMMITS=$(git log "$LAST_TAG"..HEAD --pretty=format:'%s%n%b')
+    if echo "$COMMITS" | grep -qiE 'BREAKING CHANGE:|^[a-z]+(\(.*\))?!:'; then
+      BUMP="major"
+    elif echo "$COMMITS" | grep -qE '^feat(\(.*\))?:'; then
+      BUMP="minor"
+    else
+      BUMP="patch"
+    fi
+  fi
+fi
+
+if [[ "$BUMP" != "patch" && "$BUMP" != "minor" && "$BUMP" != "major" ]]; then
+  echo "Error: invalid bump type '$BUMP' (must be patch, minor, or major)" >&2
+  exit 1
+fi
+
+# --- Bump, tag, push ---
+
+echo "Bumping $BUMP version..."
+npm version "$BUMP" -m "chore: bump version to %s" --no-git-tag-version
+
+NEW_VERSION=$(node -p "require('./package.json').version")
+git add package.json
+git commit -m "chore: bump version to $NEW_VERSION"
+git tag "v$NEW_VERSION"
+
+echo "Pushing to origin..."
+git push origin main --tags
+
+echo ""
+echo "Released v$NEW_VERSION ($BUMP bump)"
+echo "GitHub Actions release workflow will handle the rest."