restore/undo for deleted messages — backend + UI

- POST /api/channels/{id}/messages/{msg_id}/restore — undeletes a message
- Any user can restore (not just the deleter)
- Broadcasts restored message via WebSocket
- UI: "undo" button in floating pill on deleted messages
- API: restoreMessage() in api.ts

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

crates/colony/src/main.rs

@@ -53,6 +53,10 @@ async fn main() {
             "/api/channels/{channel_id}/messages/{msg_id}",
             axum::routing::delete(routes::delete_message),
         )
+        .route(
+            "/api/channels/{channel_id}/messages/{msg_id}/restore",
+            axum::routing::post(routes::restore_message),
+        )
         .route("/ws/{channel_id}", get(ws::ws_handler))
         .fallback_service(
             ServeDir::new("static").fallback(ServeFile::new("static/index.html")),

crates/colony/src/routes.rs

@@ -319,6 +319,41 @@ pub async fn delete_message(
     Ok(StatusCode::NO_CONTENT)
 }
 
+pub async fn restore_message(
+    State(state): State<AppState>,
+    Path((channel_id, msg_id)): Path<(String, String)>,
+) -> Result<impl IntoResponse> {
+    // Restore soft-deleted message (any user can restore)
+    let result = sqlx::query(
+        "UPDATE messages SET deleted_at = NULL WHERE id = ? AND channel_id = ? AND deleted_at IS NOT NULL",
+    )
+    .bind(&msg_id)
+    .bind(&channel_id)
+    .execute(&state.db)
+    .await?;
+
+    if result.rows_affected() == 0 {
+        return Err(AppError::NotFound("Message not found or not deleted".into()));
+    }
+
+    // Fetch restored message
+    let row = sqlx::query_as::<_, MessageWithUserRow>(
+        "SELECT m.*, u.id as u_id, u.username, u.display_name, u.role, u.created_at as u_created_at \
+         FROM messages m JOIN users u ON m.user_id = u.id WHERE m.id = ?",
+    )
+    .bind(&msg_id)
+    .fetch_one(&state.db)
+    .await?;
+
+    let message = row.to_api_message();
+
+    // Broadcast as new message (restored)
+    let tx = state.get_sender(&channel_id).await;
+    let _ = tx.send(WsEvent::Message(message.clone()));
+
+    Ok(Json(message))
+}
+
 // ── Joined row type for message + user ──
 
 #[derive(Debug, sqlx::FromRow)]