feat: implement time based message sweep on user ban (#670)

* feat: implement time based message sweep on user ban
- Adds `delete_message_seconds` (0 to 7 days in seconds) to the ban request payload.

Signed-off-by: arsabutispik <ispik@ispik.dev>

* refactor: pass ulid conversion to database

Signed-off-by: arsabutispik <ispik@ispik.dev>

* fix: use COL constant instead of hardcoded string in error mapper

Signed-off-by: arsabutispik <ispik@ispik.dev>

* refactor: broadcast bulk delete events during ban sweep

Updates the `delete_messages_by_author_since` trait to return a
HashMap of deleted message IDs grouped by channel.

The MongoDB implementation now uses a two-step process: it first
runs a projected `find` query to gather the target `_id` and
`channel` fields, then executes the `delete_many` operation.
This allows the ban route to loop through the affected channels and
dispatch `EventV1::BulkMessageDelete` WebSocket events, ensuring
that the swept messages are instantly removed from the UI for
all connected clients.

Signed-off-by: arsabutispik <ispik@ispik.dev>

* refactor: optimize message deletion by using $group and aggregate

Signed-off-by: arsabutispik <ispik@ispik.dev>

* refactor: use with_type in query

Signed-off-by: arsabutispik <ispik@ispik.dev>

* refactor: abstract function to Message model and mark attachments as deleted

Signed-off-by: arsabutispik <ispik@ispik.dev>

---------

Signed-off-by: arsabutispik <ispik@ispik.dev>

crates/core/models/src/v0/server_bans.rs

@@ -19,6 +19,9 @@ auto_derived!(
         /// Ban reason
         #[cfg_attr(feature = "validator", validate(length(min = 0, max = 1024)))]
         pub reason: Option<String>,
+        /// Messages to delete in seconds
+        #[cfg_attr(feature = "validator", validate(range(min = 0, max = 604800)))]
+        pub delete_message_seconds: Option<i64>,
     }
 
     /// Just enough information to list a ban