Remove wasted clones of loop-invariant values (#62763)

# Objective

Remove avoidable clones of loop-invariant values that pay a copy on
every loop iteration. These were found by running a prototype
`deep_clone_in_loop` dylint (modeled on the accidentally quadratic
project-search fix in #62658) across the workspace. None of these sites
are quadratic in practice — the loops are bounded — but each one does
strictly wasted work that a one-line change removes.

## Solution

- `collab/src/api/extensions.rs`: use `next_marker.take()` instead of
`next_marker.clone()` for the S3 pagination marker. The marker is either
overwritten via `clone_from` at the end of the iteration or the loop
breaks, so it is never read after the `take`.
- `project/src/manifest_tree/path_trie.rs`: build the trie key with
`Arc::from(path_so_far.as_rel_path())` instead of
`path_so_far.clone().into()`. The `From<RelPathBuf> for Arc<RelPath>`
impl copies the bytes into the `Arc` anyway, so the intermediate
`RelPathBuf` clone was a second, redundant copy.
- `context_server/src/client.rs`: in `notify`, split off the last
handler and move the `serde_json::Value` payload into it, cloning only
for the preceding handlers. Previously every handler received a clone
and the final one was always wasted.
- `editor/src/rewrap.rs`: use `std::mem::replace` to move the
comment-delimiter and rewrap-prefix accumulators into the pushed range
instead of cloning them and immediately reassigning.

## Testing

- `cargo check -p collab -p project -p context_server -p editor` —
clean.
- `cargo test -p editor rewrap` — 7/7 pass, including the
boundary-sensitive `test_rewrap*` editor tests.
- `cargo test -p context_server` — 97/97 pass.
- `cargo test -p project path_trie` — 2/2 pass.
- Re-ran the `deep_clone_in_loop` lint on the four crates: the
`extensions.rs`, `path_trie.rs`, and `rewrap.rs` hits are gone;
`client.rs` still (correctly) reports the remaining required per-handler
clone.
- Not tested platform-specifically; the changes are
platform-independent.

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

---

Release Notes:

- N/A

crates/collab/src/api/extensions.rs

@@ -217,7 +217,7 @@ async fn fetch_extensions_from_blob_store(
             .list_objects()
             .bucket(blob_store_bucket)
             .prefix("extensions/")
-            .set_marker(next_marker.clone())
+            .set_marker(next_marker.take())
             .send()
             .await?;
         let objects = list.contents.unwrap_or_default();

crates/context_server/src/client.rs

@@ -592,11 +592,16 @@ impl NotificationSubscriptionSet {
             return;
         };
 
+        if let Some((last_handler_id, handler_ids)) = handler_ids.split_last() {
             for handler_id in handler_ids {
                 if let Some(handler) = self.handlers.get_mut(*handler_id) {
                     handler(payload.clone(), cx.clone());
                 }
             }
+            if let Some(handler) = self.handlers.get_mut(*last_handler_id) {
+                handler(payload, cx.clone());
+            }
+        }
     }
 }
 

crates/editor/src/rewrap.rs

@@ -191,13 +191,14 @@ impl Editor {
                         Point::new(current_range_start, 0)
                             ..Point::new(prev_row, buffer.line_len(MultiBufferRow(prev_row))),
                         current_range_indent,
-                        current_range_comment_delimiters.clone(),
-                        current_range_rewrap_prefix.clone(),
+                        std::mem::replace(
+                            &mut current_range_comment_delimiters,
+                            row_comment_delimiters,
+                        ),
+                        std::mem::replace(&mut current_range_rewrap_prefix, row_rewrap_prefix),
                     ));
                     current_range_start = row;
                     current_range_indent = row_indent;
-                    current_range_comment_delimiters = row_comment_delimiters;
-                    current_range_rewrap_prefix = row_rewrap_prefix;
                 }
                 prev_row = row;
             }

crates/project/src/manifest_tree/path_trie.rs

@@ -64,9 +64,9 @@ impl<Label: Ord + Clone> RootPathTrie<Label> {
         for key in path.0.iter() {
             path_so_far = path_so_far.join(RelPath::from_unix_str(key.as_ref()).unwrap());
             current = match current.children.entry(key.clone()) {
-                Entry::Vacant(vacant_entry) => {
-                    vacant_entry.insert(RootPathTrie::new_with_key(path_so_far.clone().into()))
-                }
+                Entry::Vacant(vacant_entry) => vacant_entry.insert(RootPathTrie::new_with_key(
+                    Arc::from(path_so_far.as_rel_path()),
+                )),
                 Entry::Occupied(occupied_entry) => occupied_entry.into_mut(),
             };
         }