feat: team templates — reusable team configs with embedded skills and brief

[jousudo]

Problem

Every new project that uses chan requires manually recreating the same
team structure: brief, skills, bootstrap instructions. There is no way
to capture an organisation's standards once and apply them to new
workspaces without copy-paste.

Proposal

Add a team templates system that lets users save a complete team
configuration (name, brief, workers, skills) as a named template stored
in ~/.chan/team-templates/<name>.toml, then reuse it across projects.

Key behaviours:

• Save/load/delete templates via the team dialog in the web UI
• Applying a template to a new workspace writes config.toml,
  bootstrap.md, and all embedded skill files under .agents/skills/
  (best-effort, never overwrites existing files)
• "Import from workspace" button reads existing .agents/skills/ and
  merges them into the template form without duplicates
• cs terminal team new --template <name> for CLI-driven bootstrap
• Cross-platform: CHAN_HOME > USERPROFILE (Windows) > HOME (Unix)
• All workspace writes go through chan_workspace::Workspace; template
  storage in ~/.chan/ uses std::fs outside the workspace boundary

Implementation

I have a working implementation on my fork:
https://github.com/jousudo/chan/tree/feat/team-templates

7 commits, 16 files changed. All gates pass locally:
cargo clippy --all-targets -- -D warnings, cargo test, npm run check,
npm test -- --run (2253 tests).

Happy to adjust scope, split commits, or rework any part of this based
on your feedback before a formal PR.

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[fiorix]

This became very stale by now. Closing.