feat: Add Virtual Dev Team system with agent personas and GitHub collaboration

[haesookimDev]

Implement a team-based agent orchestration system where agents have unique
personas and collaborate through GitHub (issues, PRs, reviews, branches).

Phase 1 - Persona System:

• Add AgentPersona, PersonalityTraits types to types.rs
• Extend AgentDefinition with optional persona field
• Add persona injection to PromptComposer (7-layer prompt)
• Create 7 team member YAML definitions (PM, Tech Lead, Senior Dev,
  Frontend Dev, QA, DevOps, Junior Dev)

Phase 2 - GitHub Interaction Layer:

• New src/github_ops/ module wrapping MCP GitHub tools
• High-level APIs: create_issue, comment_on_issue, create_pr, review_pr,
  push_files, create_branch, merge_pr
• Persona-signed comments on all GitHub interactions
• github_activities SQLite table for activity tracking
• New RuntimeEvent::GitHubActivity and 8 RunActionType variants

Phase 3 - Team Workflow Engine:

• New skills/team_dev_workflow.yaml (6-stage pipeline)
• Review iteration loop: REQUEST_CHANGES triggers fix + re-review cycle
• Reuses existing DAG execution and DynamicNodeAdded patterns

Phase 4 - Frontend:

• Team dashboard page (/team) with 3 tabs
• AgentCard component with personality bars and stats
• GitHubActivityFeed with real-time activity timeline
• InteractionGraph SVG visualization of agent interactions
• Team tab added to navigation

Phase 5 - API:

• GET /v1/team/members - list team personas
• GET /v1/github/activities - list/filter GitHub activities
• GET /v1/github/activities/stats - activity statistics

Phase 6 - Configuration:

• TEAM_AGENTS_DIR, TEAM_GITHUB_REPO, TEAM_SIGN_COMMENTS env vars

https://claude.ai/code/session_01Topz63PzZxKADpS6c9Z8EX