Complete speed dial launcher helper layer; fix tile clip and arrow-nav

Wire the search-first launcher's pure helpers to their node-vm spec:
resultCountText, selectedActionId, actionLabel (accessible row/tile labels
with plugin-key disambiguation), and tileCode (collision-escalating
title/pkg/ordinal monogram). Plus three fixes surfaced by the test + review:

- visibleFavourites drops non-runnable favourites - a dead fav tile
  otherwise renders and run()s to a silent no-op on click.
- .fav-tile mirrors the list tile's inline-flex centering + 12px so a
  multi-char monogram (e.g. "EA1") no longer clips the bare button.
- Arrow Left/Right stop swallowing the search caret in the list zone;
  they only navigate when inside the favourites bar.

resources/web/dialog/SpeedDial/style.css

@@ -43,6 +43,14 @@ body {
   cursor: pointer;
   color: hsl(var(--h) var(--speed-tile-text-s, 72%) var(--speed-tile-text-l, 38%));
   font-weight: 700;
+  /* why: mirror .tile centering - tileCode can be 2-3 chars (e.g. "EA1") on collision, and a
+     bare <button> inherits 13px + UA padding, clipping the code. inline-flex + 12px + pad:0 fits it. */
+  font-size: 12px;
+  padding: 0;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  overflow: hidden;
   background: var(--speed-tile-bg, #f0f0f0);
   border: 1px solid var(--speed-tile-border, #d8d8d8);
 }