refactor: switch to dedicated group, remove @mention requirement, add pinned message service

- Change ALLOWED_GROUP to Dienst opvragen EdGPT-EBS (120363407613652082@g.us)
- Remove isBotMentioned check (no @mention needed)
- Match only exact 4-digit messages (regex /^\s*(\d{4})\s*$/)
- Add pinnedMessageService.js: auto-repins welcome message when expired
- Move incrementDaily() to count all 4-digit messages, not just successful ones
- Update daily summary with emoji
- Update docs and .env.example

src/messageHandler.js

@@ -2,28 +2,15 @@ const { findDienst, getPngFilePaths } = require('./dienstService')
 const { sendTextMessage, sendImageMessage, notifyAdmin } = require('./whatsappApi')
 const { checkLimit, increment, MAX_REQUESTS_PER_DAY } = require('./rateLimiter')
 const { increment: incrementDaily } = require('./dailyStats')
+const { checkAndRepinPinnedMessage } = require('./pinnedMessageService')
 
-const BOT_NAME = (process.env.BOT_NAME || 'EdGpt').toLowerCase()
 const ALLOWED_GROUP = process.env.ALLOWED_GROUP
 
 function extractDienstnummer(body) {
-  const match = body.match(/\b(\d{4})\b/)
+  const match = body.match(/^\s*(\d{4})\s*$/)
   return match ? match[1] : null
 }
 
-function isBotMentioned(message) {
-  if (message._data?.mentionedJidList?.length > 0) {
-    return true
-  }
-  if (message.body) {
-    const normalized = message.body.toLowerCase().replace(/\s+/g, '')
-    if (normalized.includes(`@${BOT_NAME.replace(/\s+/g, '')}`)) {
-      return true
-    }
-  }
-  return false
-}
-
 async function handleWebhook(payload) {
   if (payload.dataType !== 'message') return
   if (payload.sessionId !== process.env.WHATSAPP_SESSION) return
@@ -32,11 +19,14 @@ async function handleWebhook(payload) {
   if (!message) return
   if (message.fromMe) return
   if (message.from !== ALLOWED_GROUP) return
-  if (!isBotMentioned(message)) return
+
+  checkAndRepinPinnedMessage()
 
   const dienstnummer = extractDienstnummer(message.body || '')
   if (!dienstnummer) return
 
+  incrementDaily()
+
   console.log(`Processing dienst ${dienstnummer} for ${message.author}`)
 
   const author = message.author
@@ -50,7 +40,6 @@ async function handleWebhook(payload) {
   }
 
   increment(author)
-  incrementDaily()
 
   const dienst = findDienst(dienstnummer)
   if (!dienst) {