feat(rust): chat titles, BetterChat group styles, the voice and popups (phase 17)

PLAN.md §33, D134-D143. Protocol 12.

- Chat titles (D135-D137): per-server rules (stat, top N, text, colour)
  that rank the current wipe, and a mode (first | all | up to N). Worked
  out once in model/titles and read three ways: pushed whole to the game by
  a new titleSync loop (on change, restart or wipe), and on every
  leaderboard row as `titles`. Admin: PUT /servers/:id/titles.
- Group styles (D138, D139): a site group may carry all twelve BetterChat
  fields (rust_perm_group_chat). They ride perm.sync with `expect` from the
  pushed ledger, which gains a value column; a field changed in game is a
  `chat-field` drift row with the game's value, adopted into the style or
  put back. A withdrawn style is one `chat-group` retirement, never for
  `default`, cleared from the ledger only once BetterChat removed it.
- The voice (D140): one fleet setting naming a styled group; news and
  rust.announce chat lines carry its format and the plugin says them with
  no sender. Admin: GET/PUT /voice.
- Popups (D141, D142): rust.announce gains `delivery` (still version 1,
  from rust.options.delivery); each server gains news_delivery beside the
  news switch; `popup-unavailable` is not retried.
- GET /servers/:id/integrations reads, live, which optional mods a server
  has loaded. README lists BetterChat and PopupNotifications as optional.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

server/model/permissions/voice.js

@@ -0,0 +1,70 @@
+// ── The voice the module's own lines are said in (phase 17, D140) ──────────
+//
+// One fleet setting (§33.4 reading 5): the name of a permission group that has
+// a BetterChat style, or nothing for plain chat. News lines and `rust.announce`
+// lines are then said in that group's title and colours — composed here, said by
+// our plugin with no player as the sender, so they look right whether or not
+// BetterChat is loaded.
+//
+// The style is read at the moment a line is said, never copied into the
+// setting: an operator who recolours the group changes the voice with it, and a
+// group whose style is taken away stops being a voice rather than leaving a
+// stale one behind.
+
+const settingsDb = require('../visibility/visibility.db')
+const chatStyle = require('./chatStyle')
+const db = require('./permissions.db')
+const model = require('./permissions.model')
+
+const VOICE_KEY = 'announce.voice'
+
+/** The chosen group's name, or '' for plain chat. */
+async function chosen() {
+  return (await settingsDb.getSetting(VOICE_KEY)) || ''
+}
+
+/**
+ * The format a line is said in right now, or null for plain chat — which is
+ * also the answer when the chosen group has since lost its style or gone.
+ */
+async function currentFormat() {
+  const group = await chosen()
+  if (!group) return null
+
+  const fields = await db.getGroupChat(group)
+  return fields ? chatStyle.voiceFormat(fields) : null
+}
+
+/** The setting, and every group that could be a voice, for the admin page. */
+async function describe() {
+  const [voice, rows] = await Promise.all([chosen(), db.listGroupChat()])
+  const options = []
+
+  for (const [group, fields] of model.chatByGroup(rows)) {
+    const format = chatStyle.voiceFormat(fields)
+    if (format) options.push({ group, title: fields.Title || group, format })
+  }
+
+  return { voice, options: options.sort((a, b) => a.group.localeCompare(b.group)) }
+}
+
+/**
+ * Choose the voice. A group is accepted only when it has a style a voice can be
+ * made from; '' goes back to plain chat. Resolves `{ ok }` or
+ * `{ ok: false, message }`.
+ */
+async function choose(group, userId = null) {
+  const name = model.normaliseName(group)
+
+  if (name) {
+    const fields = await db.getGroupChat(name)
+    if (!fields || !chatStyle.voiceFormat(fields)) {
+      return { ok: false, message: `The group "${name}" has no chat style, so it cannot be a voice. Give it one under Permissions first.` }
+    }
+  }
+
+  await settingsDb.setSetting(VOICE_KEY, name, userId)
+  return { ok: true, voice: name }
+}
+
+module.exports = { VOICE_KEY, chosen, currentFormat, describe, choose }