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/db.rs

@@ -31,22 +31,10 @@ const MIGRATIONS: &[(&str, &str)] = &[
         "006",
         include_str!("../../migrations/006_merge_requests.sql"),
     ),
-    (
-        "007",
-        include_str!("../../migrations/007_documents.sql"),
-    ),
-    (
-        "008",
-        include_str!("../../migrations/008_fts5.sql"),
-    ),
-    (
-        "009",
-        include_str!("../../migrations/009_embeddings.sql"),
-    ),
-    (
-        "010",
-        include_str!("../../migrations/010_chunk_config.sql"),
-    ),
+    ("007", include_str!("../../migrations/007_documents.sql")),
+    ("008", include_str!("../../migrations/008_fts5.sql")),
+    ("009", include_str!("../../migrations/009_embeddings.sql")),
+    ("010", include_str!("../../migrations/010_chunk_config.sql")),
     (
         "011",
         include_str!("../../migrations/011_resource_events.sql"),