board: a long press on a card does what the editor's overflow does

Trash existed on Android and was three interactions deep — open the note,
tap the overflow, Move to trash — with nothing at all on the board itself.
The operator's read of that was not "the actions are in the editor"; it was
"there are no long hold context menus in the app I have no way to delete
notes." (#2946)

The card now takes `combinedClickable` and raises a DropdownMenu holding the
same items as the editor's overflow, in the same words, from the same string
resources, dispatching the same `EditorAction`s through the same
`BoardViewModel.onEditorAction`. A note has one vocabulary of things you can
do to it, and reusing the exhaustive dispatcher means the board cannot grow a
parallel one that drifts.

Gated on `note.trashed` rather than on the board's destination — the same
reading the editor uses for read-only, and the only one that survives
Reminders and search, which both mix piles.

Trash gets an UNDO snackbar rather than a confirmation. A long press is a
gesture you can make by accident, so the mistake worth designing for is the
one nobody meant to make, and a dialog only helps someone paying attention in
the moment they were not. Delete forever keeps its dialog; that one does not
undo.

`MenuItem` and the delete-forever dialog move to Panel.kt now that two
surfaces raise them, so there is one place for the close-before-acting order
and one wording of the consequences.

Colour is deliberately not in this menu, though #2946 suggested it:
`note.color` and its picker come out in #3041, so a swatch row here would be
building the one control already known to be leaving.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

android/app/src/main/res/values/strings.xml

@@ -14,6 +14,14 @@
     <!-- Board -->
     <string name="board_empty_note">Empty note</string>
 
+    <!-- The long-press menu. Its ITEMS are the editor_* strings, deliberately: a
+         note has one vocabulary of things you can do to it, and a board that said
+         "Delete" where the editor says "Move to trash" would be describing two
+         different apps. Only the wrapper and the undo need words of their own. -->
+    <string name="board_note_actions">Note actions</string>
+    <string name="board_trashed">Moved to trash</string>
+    <string name="board_undo">Undo</string>
+
     <!-- Empty states. Each destination says something true of ITSELF; a single
          "nothing here" reads as encouragement on the board and as a fault in Trash. -->
     <string name="board_empty_title">Nothing here yet</string>