tlc: phase 16 — unified MC-matching button rendering
Replace 5 dialog-specific button renderings + Dialog widget inline loop
with a single widget::button module. MC algorithm verbatim:
Normal: '[ X ]' (label + 4)
Default: '[< X >]' (label + 6)
Hotkey letter highlighted via [dialog] dhotfocus when focused,
dhotnormal otherwise. Variable button count, auto-sized, centered.
Files:
src/widget/button.rs — rewritten as free functions
(render_button, render_default_button,
render_button_row, button_width) + 5 tests
src/widget/mod.rs — re-export public API
src/widget/dialog.rs — Dialog::render button loop → render_button_row
src/terminal/popup.rs — duplicate render_button_row + push_mc_button deleted
src/filemanager/{copy,delete,link,mkdir,move}_dialog.rs — migrated
Tests: 1109 passed (was 1108; +1 widget::button).
Binaries: tlc 5.4M, tlcedit 3.9M, tlcview 3.8M.
Docs:
PLAN.md §16 — Phase 16 added (premium ratatui button pattern)
IMPROVEMENT-PLAN.md — Phase 1.5 entry marked Done
Refs: cross-referenced MC source (button.c, widget.c, tty.c) for the
exact bracket/chevron algorithm + dhotfocus/dhotnormal color picks.
vasilito
c4d4bdc586