Add backlog with v4 upgrade task

- task-001: V4 Upgrade (branch: v4)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backlog/config.yml

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+project_name: "Polycentric Web"
+default_status: "To Do"
+statuses: ["To Do", "In Progress", "Done"]
+labels: []
+milestones: []
+date_format: yyyy-mm-dd
+max_column_width: 20
+auto_open_browser: true
+default_port: 6420
+remote_operations: true
+auto_commit: false
+zero_padded_ids: 3
+bypass_git_hooks: false
+check_active_branches: true
+active_branch_days: 60

backlog/tasks/task-001 - v4-upgrade.md

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+---
+id: task-001
+title: V4 Upgrade
+status: In Progress
+assignee: []
+created_date: '2025-12-03'
+labels: [upgrade, major-version]
+priority: high
+branch: v4
+---
+
+## Description
+Upgrade to Polycentric v4 with new features and improvements.
+
+## Branch Info
+- **Branch**: `v4`
+
+## Acceptance Criteria
+- [ ] Migrate to v4 API
+- [ ] Update dependencies
+- [ ] Test all functionality