feat: add WhatsApp channel adapter (Phase 3c)

src/config/schema.ts

@@ -135,6 +135,11 @@ const slackSchema = z.object({
   allowed_channel_ids: z.array(z.string()).default([]),
 }).optional();
 
+const whatsappSchema = z.object({
+  allowed_numbers: z.array(z.string()).default([]),
+  data_dir: z.string().optional(),
+}).optional();
+
 const processSchema = z.object({
   max_concurrent: z.number().min(1).max(50).default(10),
   max_runtime_minutes: z.number().min(1).max(1440).default(60),
@@ -152,6 +157,7 @@ export const configSchema = z.object({
   telegram: telegramSchema,
   discord: discordSchema,
   slack: slackSchema,
+  whatsapp: whatsappSchema,
   server: serverSchema.default({}),
   models: modelsSchema,
   backends: backendsSchema.default({}),
@@ -177,3 +183,4 @@ export type WebSearchConfig = z.infer<typeof webSearchSchema>;
 export type ProcessConfig = z.infer<typeof processSchema>;
 export type DiscordConfig = z.infer<typeof discordSchema>;
 export type SlackConfig = z.infer<typeof slackSchema>;
+export type WhatsAppConfig = z.infer<typeof whatsappSchema>;