feat: minions plugin — Stripe-style Blueprint agents for unattended coding tasks

[Copilot]

Adds minions to the marketplace: a plugin modeled after Stripe's Minions architecture (Blueprint state machines mixing deterministic + agentic nodes) that drives Claude Code through unattended task execution — pre-hydrate context, implement, lint/test, fix once, report.

Plugin surfaces

• agents/minion.md — unattended executor enforcing the standard Blueprint sequence: deterministic pre-hydration → agentic implement → deterministic verify → one agentic fix pass (hard cap) → deterministic report
• agents/blueprint-architect.md — designs reusable Blueprint definitions for recurring task patterns; outputs .minions/<name>.blueprint.md files
• skills/blueprint/SKILL.md — encodes the D→A→D→A?→D pattern, design axioms (front-load determinism, minimize agentic surface, hard 2-pass cap), pre-hydration recipe, and verification recipe
• commands/minion.md — /minion <task|#issue|URL> fires the minion agent
• commands/blueprint.md — /blueprint [list|show|design] manages stored Blueprint files
• hooks/hooks.json + bin/minion-prehydrate.sh — UserPromptSubmit hook; pre-fetches referenced GitHub issues/PRs via gh CLI and injects content before the agent loop starts

Marketplace wiring

Entry added to .claude-plugin/marketplace.json using git-subdir source pointing to plugins/minions/ in this repo.

Key design constraints encoded

Constraint	Where enforced
One fix pass max	agents/minion.md §hard cap
Agent never commits/pushes	agents/minion.md §behavioral constraints
Pre-hydration before first agentic node	Blueprint step 1 + hook
Deterministic epilogue always runs	Blueprint step 6