feat(social): Pi-driven Russian chat replies with persistent per-player history

Replaces the canned-template "yo" path for greetings / status / addressed
banter with a Pi roundtrip that takes a real persona, the bot's current
in-game context, the operator's diary tail, AND the last 8 chat turns
with THIS specific player. Per-player cooldown (8 s) + per-message
chat-rate cooldown survive the existing throttle so a chatty player
can't drain Pi tokens.

runtime/social/chat-history.js — append/recent per player into
state/<host>/chat/<player>.jsonl, 1000-line rolling cap. Each entry
stores { ts, dir, text, snap? } where snap is a compact position +
activeSkill + milestone at the time of the turn, so Pi can later say
"помнишь когда мы тогда у воды лес рубили". Survives restarts and
auto-patch cherry-picks.

runtime/social/reply-pi.js — Russian-first system prompt locking the
bot as "pepa_bot, автономный игрок-фермер" on play.xmatic.team, one-
line answers, no emojis, no AI/bot self-mentions, no sycophancy. Spawns
`pi -p`, sanitises the response (strips pepa: prefix, code fences,
quotes, multi-line), caps at 200 chars before sending into MC chat.
Graceful: timeout/parse-fail → returns null, caller falls through to
the existing template path so the bot never goes mute.

bot.js handleChat:
- Skip messages from our own username (defensive — never reply to self).
- Record every inbound line into chat-history.
- For non-COMMAND_LIKE / non-UNSAFE intents, try piReply first; on
  success, send + record outbound; on null/throw, fall through to the
  templated generateReply.

14 new unit tests (sanitiseReply edge cases, history rotation, snap
compaction, prompt content). 190/190 green.

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

package.json

@@ -16,7 +16,7 @@
     "tui": "tsx tui/tui.tsx",
     "propose:apply": "node scripts/propose-apply.js",
     "stop": "bash scripts/stop.sh",
-    "test": "node --test runtime/skills/contract.test.js runtime/skills/groups.test.js runtime/skills/compat.test.js runtime/skills/recovery-tunnel-out.test.js runtime/curriculum.test.js runtime/social/social.test.js runtime/social/conversation.test.js runtime/stuck-incident.test.js runtime/compat.test.js runtime/reflex.test.js runtime/base-site.test.js runtime/locations.test.js runtime/watch-filter.test.js runtime/world-journal.test.js runtime/scenario-memory.test.js runtime/critic.test.js runtime/skill-library.test.js runtime/modes.test.js scripts/edit-scope.test.js scripts/lint-patch.test.js"
+    "test": "node --test runtime/skills/contract.test.js runtime/skills/groups.test.js runtime/skills/compat.test.js runtime/skills/recovery-tunnel-out.test.js runtime/curriculum.test.js runtime/social/social.test.js runtime/social/conversation.test.js runtime/social/chat-history.test.js runtime/social/reply-pi.test.js runtime/stuck-incident.test.js runtime/compat.test.js runtime/reflex.test.js runtime/base-site.test.js runtime/locations.test.js runtime/watch-filter.test.js runtime/world-journal.test.js runtime/scenario-memory.test.js runtime/critic.test.js runtime/skill-library.test.js runtime/modes.test.js scripts/edit-scope.test.js scripts/lint-patch.test.js"
   },
   "dependencies": {
     "canvas": "^3.2.3",