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_attachment.rs

@@ -0,0 +1,96 @@
+//! File / image attachment on a message — new table `message_attachment`.
+//!
+//! Discord-style: each message can have multiple attachments. Files are
+//! uploaded to S3 first, then the URL is stored here.
+
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+/// A file or image attachment on a message.
+///
+/// Maps to the `message_attachment` table. Files are uploaded to object
+/// storage first, then the URL is stored here.
+#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
+pub struct MessageAttachment {
+    pub id: Uuid,
+    pub message_id: Uuid,
+    /// Original filename as uploaded by the user.
+    pub filename: String,
+    /// MIME type: "image/png", "application/pdf", etc.
+    pub content_type: Option<String>,
+    /// File size in bytes.
+    pub size: i64,
+    /// Public URL (S3 presigned or CDN).
+    pub url: String,
+    /// S3 / object-store key for backend access.
+    pub storage_key: Option<String>,
+    /// Image / video width in pixels.
+    pub width: Option<i32>,
+    /// Image / video height in pixels.
+    pub height: Option<i32>,
+    /// Audio / video duration in seconds.
+    pub duration_secs: Option<f64>,
+    /// Blurred low-res preview for progressive loading (base64 data URI).
+    pub blurhash: Option<String>,
+    /// Whether this attachment should be rendered as a spoiler (hidden until click).
+    pub spoiler: bool,
+    pub created_at: DateTime<Utc>,
+}
+
+/// Lightweight attachment summary for list views.
+///
+/// Omits URL and storage_key to reduce payload size.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AttachmentSummary {
+    pub id: Uuid,
+    pub filename: String,
+    pub content_type: Option<String>,
+    pub size: i64,
+    pub width: Option<i32>,
+    pub height: Option<i32>,
+    pub spoiler: bool,
+}
+
+impl From<MessageAttachment> for AttachmentSummary {
+    fn from(a: MessageAttachment) -> Self {
+        Self {
+            id: a.id,
+            filename: a.filename,
+            content_type: a.content_type,
+            size: a.size,
+            width: a.width,
+            height: a.height,
+            spoiler: a.spoiler,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_attachment_conversion() {
+        let att = MessageAttachment {
+            id: Uuid::now_v7(),
+            message_id: Uuid::now_v7(),
+            filename: "photo.png".into(),
+            content_type: Some("image/png".into()),
+            size: 1024,
+            url: "https://cdn.example.com/photo.png".into(),
+            storage_key: None,
+            width: Some(800),
+            height: Some(600),
+            duration_secs: None,
+            blurhash: None,
+            spoiler: false,
+            created_at: Utc::now(),
+        };
+
+        let summary: AttachmentSummary = att.into();
+        assert_eq!(summary.filename, "photo.png");
+        assert_eq!(summary.size, 1024);
+        assert_eq!(summary.width, Some(800));
+    }
+}