Companion Buttons 1.2.0: back to picking any buttons from any pages, without the header row

1.1.0 made each tile one page, so buttons picked on a second page never
showed, choosing ended on every settings change, and a tile could go blank
after a remount. This goes back to 1.0's model and keeps only the changes
asked for:

- Pick buttons from any pages; each gets a ring and its order number.
- No Page / Clear / Done row: Page is in the gear, the grid icon starts and
  ends choosing, a second click on a button takes it out.
- Choosing survives the remount a gear change causes, so switching Page
  carries straight on.
- A tile joining a stream its dashboard already has open (another tile with
  the same buttons, or itself after a settings change) asks GET /state for
  the snapshot instead of waiting blank.
- Gear: Captions and Page. The per-page ＋ entries are gone.

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

companion.js

@@ -8,9 +8,8 @@
  *
  *   pages.watch                 → every page, its name, and which control
  *                                 sits at each row/column
- *   preview.graphics.controlId  → a button's rendered image, on every redraw
- *   controls.watchControl       → a button's setup, read once for its kind
- *                                 (page up/down buttons are left out)
+ *   preview.graphics.controlId  → a button's rendered image, following the
+ *                                 button if it is moved to another page
  *
  * Nothing here can press, edit or change anything in Companion.
  *
@@ -267,16 +266,17 @@ function createPageBook() {
     return null;
   }
 
-  /** One page by Companion's own page id (stable when pages are renumbered), or null. */
-  function page(id) {
-    return list().find((p) => p.id === id) || null;
+  /** The control at a page number, row and column right now, or null. */
+  function at(number, row, column) {
+    const page = pages.get(order[number - 1]);
+    return (page && page.controls[row] && page.controls[row][column]) || null;
   }
 
   return {
     apply,
     list,
     locate,
-    page,
+    at,
     get loaded() {
       return order.length > 0;
     },
@@ -303,7 +303,4 @@ function pageName(raw, number) {
   return `${number} ${name}`;
 }
 
-/** Companion's navigation buttons: page up, page down, the page number. Never shown. */
-const NAV_TYPES = new Set(['pageup', 'pagedown', 'pagenum']);
-
-module.exports = { createLink, createPageBook, pageName, NAV_TYPES };
+module.exports = { createLink, createPageBook, pageName };