feat(editor): hint the matching snippet in the panel on typing pause

Snapshot the snippet name inline Tab would expand into a panel field in
refresh_stats, so it rides the typing-pause throttle rather than
repainting per keystroke. Draw it as `» name` on the row above the mode
line (Latin-9 has no tab glyph), sharing the slot with the NO KBD flag,
which can't co-occur since the hint means you're typing.

docs/v0.6-markdown.md

@@ -34,11 +34,15 @@ behaviour.
       handler alongside the existing `list_marker` transform
       (`expand_snippet(word) -> Option<Snippet>`). Tab already arrives as
       `Key::Char('\t')`, so no new key event.
-- [ ] **Hint-on-pause.** On the typing pause (same throttle as the word-count /
+- [x] **Hint-on-pause.** On the typing pause (same throttle as the word-count /
       cursor refresh — never a per-keystroke repaint), if the word before the
-      caret is a prefix, the right side panel shows a quiet hint. The panel is
-      ~17 cols, so the hint is the snippet **name / first line**, not the whole
-      body — the full preview is the `$` palette's job.
+      caret is a prefix, the right side panel shows a quiet hint (`» name`, on the
+      row above the mode line, sharing the slot with the `NO KBD` flag — the two
+      never co-occur since the hint means you're typing). The panel is ~15 cols,
+      so the hint is the snippet **name**, not the whole body — the full preview is
+      the `$` palette's job. Snapshotted in `refresh_stats` so it rides the pause,
+      and the firmware's Insert-pause repaint already carries it (no firmware
+      change). Latin-9 has no `↹` glyph, hence the `»` marker.
 - [x] **`$` palette (browse + insert).** `Cmd-P` then `$` switches the palette to
       the snippet list (the same sigil mechanism as `>`). Fuzzy-matches name /
       prefix / description; Enter inserts the body at the caret and starts the