feat(whatsapp): add sendReadReceipts config option

Add option to disable automatic read receipts for WhatsApp messages.
When set to false, Clawdbot will not mark messages as read (blue ticks).

Closes #344

Changes:
- Add sendReadReceipts to WhatsAppConfig and WhatsAppAccountConfig types
- Add sendReadReceipts to zod schemas for validation
- Add sendReadReceipts to ResolvedWhatsAppAccount with fallback chain
- Pass sendReadReceipts through to monitorWebInbox
- Gate sock.readMessages() call based on config option

Default behavior (true) is preserved - only explicitly setting false
will disable read receipts.

src/config/zod-schema.providers-whatsapp.ts

@@ -13,6 +13,7 @@ export const WhatsAppAccountSchema = z
     capabilities: z.array(z.string()).optional(),
     configWrites: z.boolean().optional(),
     enabled: z.boolean().optional(),
+    sendReadReceipts: z.boolean().optional(),
     messagePrefix: z.string().optional(),
     /** Override auth directory for this WhatsApp account (Baileys multi-file auth state). */
     authDir: z.string().optional(),
@@ -62,6 +63,7 @@ export const WhatsAppConfigSchema = z
     accounts: z.record(z.string(), WhatsAppAccountSchema.optional()).optional(),
     capabilities: z.array(z.string()).optional(),
     configWrites: z.boolean().optional(),
+    sendReadReceipts: z.boolean().optional(),
     dmPolicy: DmPolicySchema.optional().default("pairing"),
     messagePrefix: z.string().optional(),
     selfChatMode: z.boolean().optional(),