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/core/events_db.rs

@@ -150,7 +150,10 @@ pub fn upsert_milestone_events(
 
 /// Resolve entity type string to (issue_id, merge_request_id) pair.
 /// Exactly one is Some, the other is None.
-fn resolve_entity_ids(entity_type: &str, entity_local_id: i64) -> Result<(Option<i64>, Option<i64>)> {
+fn resolve_entity_ids(
+    entity_type: &str,
+    entity_local_id: i64,
+) -> Result<(Option<i64>, Option<i64>)> {
     match entity_type {
         "issue" => Ok((Some(entity_local_id), None)),
         "merge_request" => Ok((None, Some(entity_local_id))),