The find bar (32..72) used to be drawn over the top of the text area,
covering the first visible line. EditorLayout now lowers the text area
top by FindBarHeight (new shared constant) while the find bar is visible;
it snaps back on close. e2e: assert the editor region top moves to
32+FindBarHeight while open.
- pool: SearchTask + FindSubstring (case-insensitive substring scan with
query generation for stale-result dropping)
- editor: FindState on EditorState; find bar handlers (ToggleFind/FindNext/
FindPrev/FindClose); worker-pool scan of the in-memory content; edit-aware
offset remapping (shift after, drop overlapping); next/prev with
wrap-around, selection + scroll to match; main-owned find_bar input
forwarded via FindQueryChan (browser search_bar precedent)
- ui: find-bar layout below the margin-free top bar; search icon on the top
bar right; new search/close/chevron_up/chevron_down icons
- logic: findQueryChan, TypeSearch result handling, findReset on open
- frame: FindQuery field (main syncs the widget text like Query)
- tests: pool scan tests, find-state unit tests (remap, nav, gen gate,
focus), e2e find bar + navigation + edit-survival on real files
- docs: spec/architecture/development_plan updated (search implemented,
channel/task tables)
