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_pin.rs

@@ -0,0 +1,60 @@
+//! Pinned message management — maps to `message_pin` table.
+//!
+//! A channel can have multiple pinned messages with explicit ordering.
+//! Unlike the `message.pinned` boolean (which just marks the row),
+//! this table tracks *who* pinned, *when*, and the display *position*.
+
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+/// One pinned message entry. Ordered by `position` ascending.
+#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
+pub struct MessagePin {
+    pub id: Uuid,
+    pub channel_id: Uuid,
+    pub message_id: Uuid,
+    /// Who pinned this message.
+    pub pinned_by: Uuid,
+    /// Display position in the pinned list (0 = top).
+    pub position: i32,
+    pub created_at: DateTime<Utc>,
+}
+
+/// Summary view returned by list-pins APIs (joined with message content).
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct PinDetail {
+    #[serde(flatten)]
+    pub pin: MessagePin,
+    pub message_body: String,
+    pub message_author_id: Uuid,
+    pub message_created_at: DateTime<Utc>,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_pin_detail_serialize() {
+        let pin = MessagePin {
+            id: Uuid::now_v7(),
+            channel_id: Uuid::now_v7(),
+            message_id: Uuid::now_v7(),
+            pinned_by: Uuid::now_v7(),
+            position: 0,
+            created_at: Utc::now(),
+        };
+
+        let detail = PinDetail {
+            pin,
+            message_body: "important announcement".to_string(),
+            message_author_id: Uuid::now_v7(),
+            message_created_at: Utc::now(),
+        };
+
+        let json = serde_json::to_value(&detail).unwrap();
+        assert_eq!(json["position"], 0);
+        assert_eq!(json["message_body"], "important announcement");
+    }
+}