zeta2: LLM-based context gathering (#41326)

Release Notes:

- N/A

---------

Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Co-authored-by: Max Brunsfeld <max@zed.dev>

crates/multi_buffer/src/multi_buffer.rs

@@ -5451,6 +5451,8 @@ impl MultiBufferSnapshot {
                     Some(OutlineItem {
                         depth: item.depth,
                         range: self.anchor_range_in_excerpt(*excerpt_id, item.range)?,
+                        source_range_for_text: self
+                            .anchor_range_in_excerpt(*excerpt_id, item.source_range_for_text)?,
                         text: item.text,
                         highlight_ranges: item.highlight_ranges,
                         name_ranges: item.name_ranges,
@@ -5484,6 +5486,11 @@ impl MultiBufferSnapshot {
                 .flat_map(|item| {
                     Some(OutlineItem {
                         depth: item.depth,
+                        source_range_for_text: Anchor::range_in_buffer(
+                            excerpt_id,
+                            buffer_id,
+                            item.source_range_for_text,
+                        ),
                         range: Anchor::range_in_buffer(excerpt_id, buffer_id, item.range),
                         text: item.text,
                         highlight_ranges: item.highlight_ranges,