chore: add release skill for automated release workflow

Add SKILL.md defining the /release command workflow with 8 steps:
1. Git branch check (must be on main, pull latest)
2. Environment check (Apple credentials, gh CLI)
3. Code quality checks (typecheck, lint, format, test)
4. Version confirmation
5. Build application
6. Commit version change
7. Generate release notes
8. Create GitHub release

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.claude/skills/release/SKILL.md

@@ -0,0 +1,186 @@
+---
+name: release
+description: Automate the Multica application release workflow including version bump, code checks, build, and GitHub release.
+---
+
+# Release Skill
+
+Automates the complete release workflow for Multica application.
+
+## How to use
+
+- `/release`
+  Start the release workflow interactively.
+
+## Release Workflow
+
+Execute the following steps in order. Stop immediately if any step fails.
+
+### Step 1: Git Branch Check
+
+1. Verify current branch is `main`
+2. Pull latest changes from remote
+3. Ensure working directory is clean (no uncommitted changes)
+
+```bash
+# Check current branch is main
+current_branch=$(git branch --show-current)
+if [ "$current_branch" != "main" ]; then
+  echo "Error: Must be on main branch. Current branch: $current_branch"
+  exit 1
+fi
+
+# Pull latest changes
+git pull origin main
+
+# Check for uncommitted changes
+if [ -n "$(git status --porcelain)" ]; then
+  echo "Error: Working directory has uncommitted changes"
+  exit 1
+fi
+```
+
+If not on main branch, abort and ask user to switch to main first.
+
+### Step 2: Environment Check
+
+1. Check if `.env` file exists in the project root
+2. Verify the following Apple credentials are set in `.env`:
+   - `APPLE_ID`
+   - `APPLE_APP_SPECIFIC_PASSWORD`
+   - `APPLE_TEAM_ID`
+3. Check GitHub CLI authentication: `gh auth status`
+4. If any check fails, inform the user what's missing and abort
+
+```bash
+# Check .env exists
+test -f .env
+
+# Check required variables (source and verify)
+source .env
+test -n "$APPLE_ID" && test -n "$APPLE_APP_SPECIFIC_PASSWORD" && test -n "$APPLE_TEAM_ID"
+
+# Check gh CLI
+gh auth status
+```
+
+### Step 3: Code Quality Checks
+
+Run all quality checks before making any changes. Abort if any fail:
+
+```bash
+pnpm typecheck      # TypeScript compilation check
+pnpm lint           # ESLint check
+pnpm format:check   # Prettier format check
+pnpm test:run       # Unit tests
+```
+
+### Step 4: Version Confirmation
+
+1. Read current version from `package.json`
+2. Ask the user for the new version number (e.g., `0.1.4`)
+3. Update the `version` field in `package.json`
+
+Use AskUserQuestion tool with options like:
+
+- Patch bump (current → next patch)
+- Minor bump (current → next minor)
+- Major bump (current → next major)
+- Custom version
+
+### Step 5: Build Application
+
+1. Clean previous build artifacts
+2. Source the environment variables
+3. Run the Mac build which creates both architectures
+
+```bash
+# Clean previous build
+rm -rf dist/
+
+# Build
+source .env && pnpm build:mac
+```
+
+This will:
+
+- Build arm64 (Apple Silicon) version
+- Build x64 (Intel) version
+- Automatically notarize with Apple (notarize: true in config)
+- Output files to `dist/` directory:
+  - `Multica-{version}-arm64.dmg`
+  - `Multica-{version}-x64.dmg`
+
+### Step 6: Commit Version Change
+
+Commit the version bump and push to remote:
+
+```bash
+git add package.json
+git commit -m "chore: bump version to {version}"
+git push origin main
+```
+
+### Step 7: Generate Release Notes
+
+1. Get the latest release tag:
+
+   ```bash
+   gh release list --limit 1 --json tagName -q '.[0].tagName'
+   ```
+
+2. Get commits since last release (or all commits if first release):
+
+   ```bash
+   # If there's a previous release tag:
+   git log {last_tag}..HEAD --oneline
+
+   # If this is the first release (no previous tag):
+   git log --oneline
+   ```
+
+3. Analyze the commits and generate release notes with sections:
+   - **New Features** - New functionality added
+   - **Bug Fixes** - Issues resolved
+   - **Improvements** - Enhancements to existing features
+   - **Other Changes** - Documentation, refactoring, etc.
+
+Format example:
+
+```markdown
+## What's New
+
+### New Features
+
+- Feature description from commit
+
+### Bug Fixes
+
+- Fix description from commit
+
+### Improvements
+
+- Improvement description from commit
+```
+
+### Step 8: Create GitHub Release
+
+1. Create the release with generated notes:
+
+   ```bash
+   gh release create v{version} \
+     --title "v{version}" \
+     --notes "{release_notes}" \
+     dist/Multica-{version}-arm64.dmg \
+     dist/Multica-{version}-x64.dmg
+   ```
+
+2. Confirm the release was created successfully
+3. Provide the release URL to the user
+
+## Important Notes
+
+- Never skip any step
+- Always wait for build completion before proceeding
+- The build process may take several minutes due to notarization
+- If build fails, check Apple credential validity