feat: implement new Git Flow workflow strategy

- Add integrate-develop.yml for automatic PR creation from develop to staging
- Add release-staging.yml for beta releases when changesets exist
- Add update-version.yml for version updates in main branch
- Add release-tag.yml for tag-based production releases
- Move old workflows to legacy folder
- Update RELEASE_STRATEGY.md and Korean version
- Create comprehensive Git Flow documentation

This new workflow implements:
- Automated PR creation: develop → staging → main
- Beta releases from staging with changesets
- Version updates in main without npm publish
- Tag-triggered production releases
- Automatic branch synchronization

Author: Seungwoo321

.github/workflows/integrate-develop.yml

@@ -0,0 +1,147 @@
+name: Integrate Develop to Staging
+
+on:
+  push:
+    branches:
+      - develop
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  create-or-update-pr:
+    name: Create or Update PR to Staging
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22.10.0'
+
+      - name: Check for existing PR
+        id: check-pr
+        run: |
+          EXISTING_PR=$(gh pr list --base staging --head develop --json number --jq '.[0].number' || echo "")
+          
+          if [ -n "$EXISTING_PR" ]; then
+            echo "pr_exists=true" >> $GITHUB_OUTPUT
+            echo "pr_number=$EXISTING_PR" >> $GITHUB_OUTPUT
+            echo "Found existing PR #$EXISTING_PR"
+          else
+            echo "pr_exists=false" >> $GITHUB_OUTPUT
+            echo "No existing PR found"
+          fi
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Get commit information
+        id: commit-info
+        run: |
+          # Get the latest commits from develop that aren't in staging
+          COMMITS=$(git log --pretty=format:"- %s (%h)" origin/staging..HEAD | head -20)
+          COMMIT_COUNT=$(git rev-list --count origin/staging..HEAD)
+          
+          # Escape for GitHub Actions output
+          COMMITS="${COMMITS//'%'/'%25'}"
+          COMMITS="${COMMITS//$'\n'/'%0A'}"
+          COMMITS="${COMMITS//$'\r'/'%0D'}"
+          
+          echo "commits<<EOF" >> $GITHUB_OUTPUT
+          echo "$COMMITS" >> $GITHUB_OUTPUT
+          echo "EOF" >> $GITHUB_OUTPUT
+          echo "commit_count=$COMMIT_COUNT" >> $GITHUB_OUTPUT
+          
+          # Get timestamp
+          TIMESTAMP=$(date -u +"%Y-%m-%d %H:%M:%S UTC")
+          echo "timestamp=$TIMESTAMP" >> $GITHUB_OUTPUT
+
+      - name: Create PR to staging
+        if: steps.check-pr.outputs.pr_exists == 'false'
+        run: |
+          gh pr create \
+            --base staging \
+            --head develop \
+            --title "🔄 Integrate develop → staging" \
+            --body "## 🚀 Integration from develop to staging
+
+### 📊 Summary
+- **Commits**: ${{ steps.commit-info.outputs.commit_count }} new commits
+- **Created**: ${{ steps.commit-info.outputs.timestamp }}
+- **Auto-generated**: This PR was automatically created by the integration workflow
+
+### 📝 Recent Commits
+${{ steps.commit-info.outputs.commits }}
+
+### 🔍 What happens next?
+1. Review the changes in this PR
+2. Run any necessary QA tests
+3. When approved and merged, the staging workflow will:
+   - Check for changesets
+   - If found, create beta releases
+   - Automatically create a PR to main
+
+### ⚡ Notes
+- This PR will be automatically updated with new commits to develop
+- Multiple features can accumulate in this single PR
+- Approval triggers the beta release process" \
+            --label "integration" \
+            --label "automated"
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Update existing PR
+        if: steps.check-pr.outputs.pr_exists == 'true'
+        run: |
+          # Update PR title with commit count
+          gh pr edit ${{ steps.check-pr.outputs.pr_number }} \
+            --title "🔄 Integrate develop → staging (${{ steps.commit-info.outputs.commit_count }} commits)"
+          
+          # Get current PR body
+          CURRENT_BODY=$(gh pr view ${{ steps.check-pr.outputs.pr_number }} --json body --jq '.body')
+          
+          # Create updated section
+          UPDATED_SECTION="### 🔄 Last Updated: ${{ steps.commit-info.outputs.timestamp }}
+**New commits**: ${{ steps.commit-info.outputs.commit_count }}
+
+### 📝 Recent Commits
+${{ steps.commit-info.outputs.commits }}"
+          
+          # Update or append the updated section
+          if echo "$CURRENT_BODY" | grep -q "### 🔄 Last Updated:"; then
+            # Replace existing update section
+            NEW_BODY=$(echo "$CURRENT_BODY" | sed '/### 🔄 Last Updated:/,/### 📝 Recent Commits/d' | sed '/^$/d')
+            NEW_BODY="$NEW_BODY
+
+$UPDATED_SECTION"
+          else
+            # Append update section
+            NEW_BODY="$CURRENT_BODY
+
+---
+
+$UPDATED_SECTION"
+          fi
+          
+          # Update PR body
+          gh pr edit ${{ steps.check-pr.outputs.pr_number }} --body "$NEW_BODY"
+          
+          # Add labels
+          gh pr edit ${{ steps.check-pr.outputs.pr_number }} \
+            --add-label "auto-updated" \
+            --add-label "needs-review"
+          
+          # Set as ready for review
+          gh pr ready ${{ steps.check-pr.outputs.pr_number }} || true
+          
+          echo "✅ Updated PR #${{ steps.check-pr.outputs.pr_number }} with ${{ steps.commit-info.outputs.commit_count }} new commits"
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}