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/embedding/chunking.rs

@@ -78,7 +78,9 @@ pub fn split_into_chunks(content: &str) -> Vec<(usize, String)> {
 fn find_paragraph_break(window: &str) -> Option<usize> {
     // Search backward from 2/3 of the way through to find a good split
     let search_start = window.len() * 2 / 3;
-    window[search_start..].rfind("\n\n").map(|pos| search_start + pos + 2)
+    window[search_start..]
+        .rfind("\n\n")
+        .map(|pos| search_start + pos + 2)
         .or_else(|| window[..search_start].rfind("\n\n").map(|pos| pos + 2))
 }
 
@@ -102,7 +104,9 @@ fn find_sentence_break(window: &str) -> Option<usize> {
 /// Find the last word boundary (space) in the window.
 fn find_word_break(window: &str) -> Option<usize> {
     let search_start = window.len() / 2;
-    window[search_start..].rfind(' ').map(|pos| search_start + pos + 1)
+    window[search_start..]
+        .rfind(' ')
+        .map(|pos| search_start + pos + 1)
         .or_else(|| window[..search_start].rfind(' ').map(|pos| pos + 1))
 }
 
@@ -155,7 +159,11 @@ mod tests {
         }
 
         let chunks = split_into_chunks(&content);
-        assert!(chunks.len() >= 2, "Expected multiple chunks, got {}", chunks.len());
+        assert!(
+            chunks.len() >= 2,
+            "Expected multiple chunks, got {}",
+            chunks.len()
+        );
 
         // Verify indices are sequential
         for (i, (idx, _)) in chunks.iter().enumerate() {
@@ -183,7 +191,8 @@ mod tests {
             let end_of_first = &chunks[0].1;
             let start_of_second = &chunks[1].1;
             // The end of first chunk should overlap with start of second
-            let overlap_region = &end_of_first[end_of_first.len().saturating_sub(CHUNK_OVERLAP_CHARS)..];
+            let overlap_region =
+                &end_of_first[end_of_first.len().saturating_sub(CHUNK_OVERLAP_CHARS)..];
             assert!(
                 start_of_second.starts_with(overlap_region)
                     || overlap_region.contains(&start_of_second[..100.min(start_of_second.len())]),