fix: v0.1.11 — fix crypto_box decryption with session pubkeys

Store sender's sessionPubkey on message_queue at send time.
drainForMember returns COALESCE(sender_session_pubkey, peer_pubkey)
so the recipient gets the correct sender key for decryption.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/db/migrations/0006_add-sender-session-pubkey.sql

@@ -0,0 +1 @@
+ALTER TABLE "mesh"."message_queue" ADD COLUMN "sender_session_pubkey" text;

packages/db/src/schema/mesh.ts

@@ -222,6 +222,7 @@ export const messageQueue = meshSchema.table("message_queue", {
   senderMemberId: text()
     .references(() => meshMember.id, { onDelete: "cascade", onUpdate: "cascade" })
     .notNull(),
+  senderSessionPubkey: text(),
   targetSpec: text().notNull(),
   priority: messagePriorityEnum().notNull().default("next"),
   nonce: text().notNull(),