Use composable autocomplete provider in pi-fff (dmtrKovalenko#570)

refactor(nvim): split monolithic picker_ui.lua into focused submodules (

dmtrKovalenko#564)

* refactor(picker_ui): split monolithic picker_ui.lua into focused submodules

Break the ~2535-line picker_ui.lua into 8 modules under lua/fff/picker_ui/:
- state_manager.lua: pure data store for all picker state
- ui_creator.lua: buffers, windows, keymaps, autocmds
- search_manager.lua: search execution, pagination, query history
- renderer.lua: list rendering, combo separator, scrollbar, empty state
- preview_manager.lua: preview debounce, title, update/clear
- navigation.lua: cursor movement, pagination wrap, preview scrolling
- layout_manager.lua: relayout on VimResized, close/cleanup
- init.lua: coordinator wiring all submodules via init(P) pattern

Move picker_ui.lua to picker_ui/init.lua for clean module resolution.

Also removes unused scrollbar import in ui_creator.lua and need-check-nil
diagnostic suppression comments in preview_manager.lua (nil was already
handled by the guard check).

* feat: rename and create utils in picker_ui

* chore: move list_renderer and combo_renderer

* feat: move grep_renderer and list_renderer

* chore: fix lint

* chore: update readme

feat(nvim): Make `move_up` and `move_down` work in normal mode.

chore: release 0.9.1

chore: release 0.9.1

fix: Error on file update if indexed 0 files (dmtrKovalenko#569)

Release 0.9.1

chore(ci): Bump the version not bumped automatically

chore(ci): Bump the version not bumped automatically

fix(preview): keep cursor on match when paging with <C-d>/<C-u> (dmtr…

…Kovalenko#556)

* fix(preview): keep cursor on match when paging with <C-d>/<C-u>

preview.scroll moved the cursor to the new topline, which dragged the
location highlight / cursorline away from the matched line. Page the
viewport with winrestview({topline=...}) instead so cursor stays parked
on the match.

Refs dmtrKovalenko#555

* fix: Properly address the issue

---------

Co-authored-by: gustav-fff <286169375+gustav-fff@users.noreply.github.com>
Co-authored-by: Dmitriy Kovalenko <dmtr.kovalenko@outlook.com>