Realign code with the 2026-07-30 findings-resolution rulings

Delete Immediately is removed entirely (ruling ae1dd96, Redesign card
d40bfac1): the delete vocabulary is purely staged — board → trash,
trash → permanent (confirmed on no-git boards), Empty Trash for bulk.
Gone: File ▸ Delete Immediately (⌥⌘⌫) and its validation, both
⌥-alternate context rows (card + the permanently-disabled lane row),
the VO custom action, BoardStore.deleteImmediately,
TrashModel.canDeleteImmediately, TrashConfirmations' .purge action
(zero surviving callers — trash-side Delete always used
.deleteTrashCards), and the pinning tests. purgePrompt drops its
now-single-purpose container parameter (.trash is the only surviving
caller). BoardWriter.purgeItem survives — create-undo rollback still
needs it — with its comment rewritten. README's trash paragraph drops
the ⌥⌘⌫ sentence.

The other 2026-07-30 rulings (2ec2c95 registry freshness stamp,
c741b02 unified-log-as-coerce-consumer) required no code changes —
already conformant.

Both schemes 1844 tests / 318 suites green.

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

KanbanTests/UndoWriteTests.swift

@@ -811,7 +811,7 @@ struct BodyUndoTests {
 @Suite("Undo ▸ the operations that register nothing")
 struct NotUndoableTests {
 
-    @Test("Delete Immediately registers nothing — the confirm is the safety")
+    @Test("The trash's permanent delete registers nothing — the confirm is the safety")
     func purgeRegistersNothing() throws {
         let fixture = try makeBoard()
         defer { fixture.tearDown() }
@@ -820,7 +820,7 @@ struct NotUndoableTests {
         let armed = try #require(history.undoActionName)
 
         store.select([trashed], in: .trash)
-        store.deleteImmediately([trashed], in: .trash)
+        store.deleteTrashCards([trashed])
 
         #expect(fixture.exists(trashedPath) == false)
         #expect(store.purgeIsUnrecoverable)