feat(discord): connector pilot for the Sage seat, reviewed candidate (#1509)

Zero-dependency Discord connector under packages/discord: binding
validation, REST and gateway clients, pi engine adapter, journal with
append-only inbox, outbox, admissions and notices, and a run.lock
ownership record {pid, start, boot} whose identity is checked three ways
and whose cleanup is gated by STOP. CLI check|run|stop|unlock via
scripts/discord.sh; offline suite scripts/test-discord.sh (28 checks,
87 node tests).

Reviewed by rev-code-02 on #1509 over nine rounds; approved exact tree
4e0feb6758c0a7e4a71483912a8e0d3e3ec95aef at comment 26170. Corrections
(1) to (12) recorded in BUILD-LOG. No listener started, no token read,
no Discord write; the live pilot follows this commit per the brief.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

packages/discord/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "@mosaic/discord",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Discord connector: one seat's conversation reachable from listed channels of one server, chat only, with write-once records for every accepted message, turn and delivery.",
+  "license": "UNLICENSED",
+  "type": "module",
+  "engines": { "node": ">=24" },
+  "bin": { "mosaic-discord": "src/cli.mjs" },
+  "exports": { ".": "./src/connector.mjs" },
+  "scripts": { "test": "node --test tests/" }
+}