feat(WHE-21): scaffold grammy webhook bot server

apps/bot/src/config.ts

@@ -0,0 +1,36 @@
+export interface BotRuntimeConfig {
+  port: number
+  telegramBotToken: string
+  telegramWebhookSecret: string
+  telegramWebhookPath: string
+}
+
+function parsePort(raw: string | undefined): number {
+  if (raw === undefined) {
+    return 3000
+  }
+
+  const parsed = Number(raw)
+  if (!Number.isInteger(parsed) || parsed <= 0 || parsed > 65535) {
+    throw new Error(`Invalid PORT value: ${raw}`)
+  }
+
+  return parsed
+}
+
+function requireValue(value: string | undefined, key: string): string {
+  if (!value || value.trim().length === 0) {
+    throw new Error(`${key} environment variable is required`)
+  }
+
+  return value
+}
+
+export function getBotRuntimeConfig(env: NodeJS.ProcessEnv = process.env): BotRuntimeConfig {
+  return {
+    port: parsePort(env.PORT),
+    telegramBotToken: requireValue(env.TELEGRAM_BOT_TOKEN, 'TELEGRAM_BOT_TOKEN'),
+    telegramWebhookSecret: requireValue(env.TELEGRAM_WEBHOOK_SECRET, 'TELEGRAM_WEBHOOK_SECRET'),
+    telegramWebhookPath: env.TELEGRAM_WEBHOOK_PATH ?? '/webhook/telegram'
+  }
+}