style: Apply cargo fmt and clippy fixes across codebase

Automated formatting and lint corrections from parallel agent work:

- cargo fmt: import reordering (alphabetical), line wrapping to respect
  max width, trailing comma normalization, destructuring alignment,
  function signature reformatting, match arm formatting
- clippy (pedantic): Range::contains() instead of manual comparisons,
  i64::from() instead of `as i64` casts, .clamp() instead of
  .max().min() chains, let-chain refactors (if-let with &&),
  #[allow(clippy::too_many_arguments)] and
  #[allow(clippy::field_reassign_with_default)] where warranted
- Removed trailing blank lines and extra whitespace

No behavioral changes. All existing tests pass unmodified.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/ingestion/mr_discussions.rs

@@ -19,13 +19,13 @@ use crate::core::error::Result;
 use crate::core::payloads::{StorePayloadOptions, store_payload};
 use crate::core::time::now_ms;
 use crate::documents::SourceType;
-use crate::ingestion::dirty_tracker;
 use crate::gitlab::GitLabClient;
 use crate::gitlab::transformers::{
     NormalizedDiscussion, NormalizedNote, transform_mr_discussion,
     transform_notes_with_diff_position,
 };
 use crate::gitlab::types::GitLabDiscussion;
+use crate::ingestion::dirty_tracker;
 
 use super::merge_requests::MrForDiscussionSync;
 
@@ -72,7 +72,10 @@ pub async fn prefetch_mr_discussions(
     debug!(mr_iid = mr.iid, "Prefetching discussions for MR");
 
     // Fetch all discussions from GitLab
-    let raw_discussions = match client.fetch_all_mr_discussions(gitlab_project_id, mr.iid).await {
+    let raw_discussions = match client
+        .fetch_all_mr_discussions(gitlab_project_id, mr.iid)
+        .await
+    {
         Ok(d) => d,
         Err(e) => {
             return PrefetchedMrDiscussions {
@@ -241,7 +244,10 @@ pub fn write_prefetched_mr_discussions(
         mark_discussions_synced(conn, mr.local_mr_id, mr.updated_at)?;
         clear_sync_health_error(conn, mr.local_mr_id)?;
 
-        debug!(mr_iid = mr.iid, "MR discussion sync complete, watermark advanced");
+        debug!(
+            mr_iid = mr.iid,
+            "MR discussion sync complete, watermark advanced"
+        );
     } else if prefetched.had_transform_errors {
         warn!(
             mr_iid = mr.iid,