feat(init): add guided cross-platform onboarding

[whitelonng]

What changed

• Allow beginners to initialize safe empty directories without requiring Git or npm init -y.
• Add localized interactive platform selection for Claude Code, Cursor, Codex, Copilot, and ZCode, including multi-select and all.
• Add mancode refresh-project so projects can safely pick up Git or manifests added later.
• Preserve explicit team-mode choices and refresh installed static adapters transactionally.
• Expand Windows CMD, PowerShell, and Git Bash smoke coverage.
• Synchronize English/Chinese README and website documentation.

Why

The previous initialization flow rejected new folders and treated Bash/Git as universal prerequisites. That blocked first-time users, especially on native Windows, and did not clearly guide them through choosing an agent platform.

Impact

Initialization is now beginner-friendly and native across supported shells. Platform detection remains a hint rather than silently installing every adapter, while refresh keeps project metadata current when the folder evolves.

Validation

• npm run lint
• npm run typecheck
• npm test (396 tests)
• npm run build
• npm run test:windows-smoke
• git diff --check