feat(service): expand service layer with new domain operations

- Add IM service modules: audit, channel roles, custom emojis, forum
  tags, integrations, invitations, repo links, slash commands, stages,
  voice, webhooks
- Add PR service modules: review requests, templates
- Add repo service modules: contributors, release assets, git extras
  (archive, branch rename, commit extras, diff/merge, tag, tree)
- Add user service: social (follow/block)
- Add internal auth service
- Update existing service modules with expanded functionality
- Remove deleted IM modules: articles, delivery trace, drafts,
  follows, messages, polls, presence, reactions, threads

service/im/audit.rs

@@ -0,0 +1,32 @@
+use uuid::Uuid;
+
+use crate::error::AppError;
+use crate::models::channels::ChannelEvent;
+use crate::service::ImService;
+
+use super::session::ImSession;
+
+impl ImService {
+    pub async fn audit_list(
+        &self,
+        _ctx: &ImSession,
+        channel_id: Uuid,
+        limit: i64,
+        offset: i64,
+    ) -> Result<Vec<ChannelEvent>, AppError> {
+        let limit = limit.clamp(1, 100);
+        let offset = offset.max(0);
+        sqlx::query_as::<_, ChannelEvent>(
+            "SELECT id, channel_id, actor_id, event_type, target_type, target_id, \
+             old_value, new_value, metadata, created_at \
+             FROM channel_event WHERE channel_id = $1 \
+             ORDER BY created_at DESC LIMIT $2 OFFSET $3",
+        )
+        .bind(channel_id)
+        .bind(limit)
+        .bind(offset)
+        .fetch_all(self.ctx.db.reader())
+        .await
+        .map_err(AppError::Database)
+    }
+}