refactor(tests): reformat code and update dependency management

- Reorganized import statements in adapter tests for better readability
- Replaced or_insert_with(Vec::new) with or_default() in test closures
- Updated Cargo.lock with new dependency versions and checksums
- Added TLS features to tonic dependency configuration
- Included sqlx, chrono, and uuid dependencies with specific features
- Added jsonwebtoken and arc-swap as project dependencies
- Reformatted assertion statements to comply with line length limits
- Adjusted base64 import order in engine codec module
- Updated protobuf include statement formatting

models/message_reaction.rs

@@ -0,0 +1,66 @@
+//! Emoji reaction on a message — maps to `message_reaction` table.
+//!
+//! One row per (user, message, emoji). `content` stores the emoji string
+//! (Unicode emoji or custom `:name:id` format like Discord).
+
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+/// A single emoji reaction on a message by a user.
+///
+/// Maps to the `message_reaction` table. One row per (user, message, emoji).
+#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
+pub struct MessageReaction {
+    pub id: Uuid,
+    pub message_id: Uuid,
+    pub channel_id: Uuid,
+    pub user_id: Uuid,
+    /// Emoji string: "👍", "🎉", or custom ":appks:01909a..."
+    pub content: String,
+    pub created_at: DateTime<Utc>,
+}
+
+/// Aggregated reaction count for a single emoji on a message.
+/// Returned in [`MessageDetail::reactions`] and list APIs.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ReactionCount {
+    pub content: String,
+    pub count: i64,
+    /// Whether the current user reacted with this emoji.
+    pub me: bool,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_reaction_serialize() {
+        let reaction = MessageReaction {
+            id: Uuid::now_v7(),
+            message_id: Uuid::now_v7(),
+            channel_id: Uuid::now_v7(),
+            user_id: Uuid::now_v7(),
+            content: "👍".into(),
+            created_at: Utc::now(),
+        };
+
+        let json = serde_json::to_value(&reaction).unwrap();
+        assert_eq!(json["content"], "👍");
+    }
+
+    #[test]
+    fn test_reaction_count_serialize() {
+        let count = ReactionCount {
+            content: "🎉".into(),
+            count: 3,
+            me: true,
+        };
+
+        let json = serde_json::to_value(&count).unwrap();
+        assert_eq!(json["content"], "🎉");
+        assert_eq!(json["count"], 3);
+        assert_eq!(json["me"], true);
+    }
+}