feat(gh-aw): /squad from {url} — Connect mode (remote squad) #1615

/squad from {url} — Connect Mode

Part of #1612 (Squad Agentic Workflows epic).
Depends on: #1613 (shared/squad.md bootstrap component)

Overview

Enterprise mode for organizations that maintain a centralized squad definition. The target repo gets a lightweight config pointer; the actual squad files are pulled at activation time from the remote source.

Trigger Pattern

• /squad from acme-corp/our-squad
• /squad from org/squad-templates/enterprise-team

Agent Behavior

1. Parse the squad-source URL from the command
2. Validate the source repo is accessible (with provided token if cross-org)
3. Write minimal .squad/config.json:

   {
     "squadSource": "acme-corp/our-squad",
     "mode": "connect"
   }

4. Generate meet-the-squad.md noting the squad is externally managed
5. Open PR with only the config pointer + meet-the-squad doc

Key Design Decisions

• Squad files are NEVER committed to the target repo — only the config pointer
• The shared/squad.md bootstrap component handles pulling remote squad at activation time
• This enables centralized squad governance: update once, all connected repos get the change
• Cross-org access requires GitHub App token (configured via component input)

PR Content

Minimal footprint:

• .squad/config.json (the pointer)
• meet-the-squad.md (notes squad is externally managed, links to source)

Acceptance Criteria

• /squad from org/repo triggers Connect mode
• .squad/config.json is written with correct squadSource and mode: "connect"
• Squad files from source are NOT committed to target repo
• meet-the-squad.md clearly states the squad is externally managed
• PR contains only config pointer + meet-the-squad.md
• Bootstrap component (shared/squad.md) correctly pulls remote squad at activation
• Cross-org access works with GitHub App token
• Invalid/inaccessible source URLs produce clear error messages