chore: bootstrap pepa-pi-bot scaffold

Initial seed for an autonomous, self-extending Minecraft player powered by
Pi (pi.dev) and Mineflayer.

Includes README, AGENTS.md mandate, .env.example, MIT LICENSE, package.json
with mineflayer + dotenv, and empty skills/ extensions/ prompts/ dirs for
the agent to grow into.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

prompts/.gitkeep

@@ -0,0 +1,2 @@
+# Reusable prompt templates (markdown).
+# Good first one: `tick.md` — what the autonomous tick should consider.