feat(perception): vendor mindcraft skills/world library + Pi tool wrappers

The bot was acting blind: it knew its own coordinates but nothing about
what was around it. mc_goto's over-strict safety guards refused every
real path. mc_dig was too low-level to drive a coherent farming loop.
The result: 4+ hours of "trying" with zero physical achievement.

This commit reframes the bridge around a perceive→decide→act loop using
proven primitives from Mindcraft (github.com/kolbytn/mindcraft, MIT —
LICENSE-MINDCRAFT vendored beside the library files).

Changes:

- extensions/lib/  (new, vendored from Mindcraft with attribution)
  - world.js  (431 LoC) — 21 perception functions: getNearbyBlockTypes,
    getNearbyEntities, getInventoryCounts, getNearestBlock, getPosition,
    getBiomeName, etc.
  - skills.js (2093 LoC) — 30+ action primitives: collectBlock, placeBlock,
    goToPosition, goToNearestBlock, craftRecipe, equip, consume,
    defendSelf, avoidEnemies, pickupNearbyItems, stay, etc.
  - mcdata.js (~600 LoC) — Mindcraft's mc-data adapter. Imports patched
    to local paths; mineflayer-auto-eat removed (our installed 5.x has
    a divergent API; skills.consume() falls back to bot.consume()).
    Added attachPluginsAndInit(bot) export so mineflayer-bridge.ts can
    wire plugins onto its externally-created bot.
  - settings.js — minimal stub with farmer-bot defaults.

- extensions/mindcraft-skills.ts (new, 406 LoC) — Pi extension registering
  15 high-level tools on top of the vendored library:
  - Perception: mc_observe, mc_inventory, mc_nearby_blocks, mc_nearby_entities
  - Action: mc_collect_block, mc_place_block, mc_go_to, mc_go_to_block,
    mc_craft, mc_equip, mc_consume, mc_defend_self, mc_avoid_enemies,
    mc_stay, mc_pickup_nearby
  ES modules from extensions/lib/ are loaded via dynamic import() at
  extension init so the cross-extension require()-race resolves cleanly.

- extensions/mineflayer-bridge.ts
  - Expose the live Mineflayer bot on globalThis.__pepaPiBot so the
    mindcraft-skills extension can use it (set on connect, cleared on
    error/end/manual disconnect).
  - Call attachPluginsAndInit(nextBot) right after createBot to load
    pathfinder, pvp, collectblock, armorManager and prime
    minecraft-data once login completes.

- package.json — new runtime deps: minecraft-data, vec3,
  mineflayer-pvp, prismarine-item.

- AGENTS.md — new "Perception → decision → action" section before
  "Your tools right now" with full tool catalog and a deprecation
  note for the broken mc_goto / mc_build_pyramid_5x5 / low-level
  mc_dig from the old bridge.

Smoke test (medium thinking): bot called mc_observe and received a
real JSON snapshot — nearbyBlocks listed coal_ore, oak_log, water,
sand; nearbyEntityTypes listed creeper, zombie, pillager, skeleton.
The bot can finally see what it could not see this morning.

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

extensions/lib/settings.js

@@ -0,0 +1,11 @@
+// Minimal settings stub adapted from Mindcraft for the pepa-pi-bot vendored
+// world.js / skills.js / mcdata.js library. Mindcraft expects a settings module
+// with these defaults; we use sane farmer-bot values.
+//
+// Source: github.com/kolbytn/mindcraft (MIT)
+export default {
+    block_place_delay: 0,
+    minecraft_version: "auto",
+    allow_insecure_coding: false,
+    log_all_prompts: false,
+};