Add per-staff metrics: StaffAction event log + /stats command

Event-sourced tracking of staff/ticket lifecycle actions, plus a /stats
command. Foundation for a future tickets-website analytics dashboard.

Data:
- StaffAction model (event log) + Ticket.game / Ticket.closedAt
- STATS_ADMIN_IDS config (who may view others' stats)

Recording (fire-and-forget, idempotent on real state transitions):
- claim, response (channel reply + /response send), escalate, de-escalate,
  transfer, close (4 sites), reopen — each denormalizes ticketType, tier,
  priority, game, requester (senderEmail / creatorId), guildId
- close events carry closerType / resolverId (claimer credit) / wasClaimed;
  transfer carries fromId / toId; reopen stamps resolverId
- conditional close transition helper (atomic open->closed + closedAt) shared
  by all four close paths

Query + command:
- pure period parser (presets + free-text) and stats shaper (per-metric keys)
- command-aware autocomplete dispatch
- /stats: period (autocomplete) + member (admin-gated) + source (all/email/
  discord), ManageMessages + staff-role gated, ephemeral, tier-labeled embed

288+ unit tests; timing/busiest-times data is collected but displayed later.

tests/configSchema.test.js

@@ -19,6 +19,10 @@ describe('ALLOWED_CONFIG_KEYS', () => {
     }
   });
 
+  it('includes STATS_ADMIN_IDS', () => {
+    expect(ALLOWED_CONFIG_KEYS.has('STATS_ADMIN_IDS')).toBe(true);
+  });
+
   it('does not contain stale removed keys', () => {
     for (const k of ['BOSSCORD_API_KEY', 'SURGE_ENABLED']) {
       expect(ALLOWED_CONFIG_KEYS.has(k)).toBe(false);
@@ -192,9 +196,8 @@ describe('discord_id validator', () => {
 
 describe('discord_id_list validator', () => {
   // ADDITIONAL_STAFF_ROLES (a real comma-list) ends in _ROLES, not _IDS, so it
-  // hits the string fallback. discord_id_list only fires for `*_IDS` keys, so
-  // exercise it with a hypothetical name.
-  const v = getValidator('STAFF_USER_IDS');
+  // hits the string fallback. discord_id_list only fires for `*_IDS` keys.
+  const v = getValidator('STATS_ADMIN_IDS');
 
   it('infers type discord_id_list for *_IDS keys', () => {
     expect(v.type).toBe('discord_id_list');
@@ -221,6 +224,40 @@ describe('discord_id_list validator', () => {
   });
 });
 
+describe('STATS_ADMIN_IDS parsing (config.js pattern)', () => {
+  // Tests the .split(',').map(r=>r.trim()).filter(Boolean) idiom used for all
+  // list env vars in config.js — exercised here as a pure expression.
+  function parseIdList(v) {
+    return (v || '').split(',').map(r => r.trim()).filter(Boolean);
+  }
+
+  it('returns [] for empty string', () => {
+    expect(parseIdList('')).toEqual([]);
+  });
+
+  it('returns [] for undefined', () => {
+    expect(parseIdList(undefined)).toEqual([]);
+  });
+
+  it('returns a single-element array for one ID', () => {
+    expect(parseIdList('321754640431710226')).toEqual(['321754640431710226']);
+  });
+
+  it('returns multiple IDs for comma-separated input', () => {
+    expect(parseIdList('321754640431710226,691678135527276614,224692549225283584'))
+      .toEqual(['321754640431710226', '691678135527276614', '224692549225283584']);
+  });
+
+  it('trims whitespace around each ID', () => {
+    expect(parseIdList(' 321754640431710226 , 691678135527276614 '))
+      .toEqual(['321754640431710226', '691678135527276614']);
+  });
+
+  it('drops empty segments from trailing commas', () => {
+    expect(parseIdList('321754640431710226,')).toEqual(['321754640431710226']);
+  });
+});
+
 describe('string validator (fallback)', () => {
   const v = getValidator('TICKET_CATEGORY_NAME');