Files: recent and found files keep the cursor on the file, not its place

RecentFiles and FileSearch keyed their rows by place in the list, so when
an open moved a file to the top, the cursor stayed at the place and the
next Enter opened another file. Rows are keyed by the file's folder and
name, asserted once a list, so the cursor follows the file. A dotfile's
kind reads by its extension, as its icon does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

TASKS.md

@@ -325,3 +325,4 @@ Per-component lines live in `tasks/`. Tags there:
 | T27a | 2 | PASS | |
 | T27b | 1 | FAIL | the listing's fixed columns left no room for names at 280px; a column keyed by its depth handed its cursor to the next folder there |
 | T27b | 2 | PASS | |
+| T27c | 1 | FAIL | recent and found files were keyed by their place, so the cursor left a file an open moved |