Initial commit: split VNOX monorepo into VNOX-Server

Unified server binary (vnox-serverd) combining:
- Gateway (TCP, auth, channels, sessions, SQLite)
- Voice-node (UDP relay, Opus, jitter buffer)

Standalone gateway (vnox-gateway) and voice-node (vnox-voice-node) preserved as sub-crates.

gateway/src/domain/storage/dm_unread.rs

@@ -0,0 +1,38 @@
+use anyhow::Result;
+
+impl super::Storage {
+    pub async fn increment_dm_unread(&self, dm_id: &str, recipient_id: &str) -> Result<()> {
+        let (u1, _u2) = sqlx::query_as::<_, (String, String)>(
+            "SELECT user1_id,user2_id FROM direct_messages WHERE id=?",
+        )
+        .bind(dm_id)
+        .fetch_one(&self.pool)
+        .await?;
+        if recipient_id == u1 {
+            sqlx::query("UPDATE direct_messages SET unread_count_2=unread_count_2+1 WHERE id=?")
+                .bind(dm_id)
+                .execute(&self.pool)
+                .await?;
+        } else {
+            sqlx::query("UPDATE direct_messages SET unread_count_1=unread_count_1+1 WHERE id=?")
+                .bind(dm_id)
+                .execute(&self.pool)
+                .await?;
+        }
+        Ok(())
+    }
+
+    pub async fn reset_dm_unread(&self, dm_id: &str, user_id: &str) -> Result<()> {
+        sqlx::query(
+            "UPDATE direct_messages SET \
+             unread_count_1 = CASE WHEN user1_id=? THEN 0 ELSE unread_count_1 END, \
+             unread_count_2 = CASE WHEN user2_id=? THEN 0 ELSE unread_count_2 END WHERE id=?",
+        )
+        .bind(user_id)
+        .bind(user_id)
+        .bind(dm_id)
+        .execute(&self.pool)
+        .await?;
+        Ok(())
+    }
+}