Materialize the trash — store, undo, and the container universe

Phase 2 swaps every consumer: Liveness and its ancestor walk are gone,
replaced by ItemContainer — a UUID set plus the container side it
lives on, presence the whole test, one selection boundary instead of
the old liveness law. Deletion stages by place: board cards move to
the trash at a store-minted head rank, trash-side delete is permanent
behind its confirmation, Delete Immediately skips the trash from
anywhere, lane delete captures the subtree and removes the folder.
Restore has no method at all — moveCards resolves members in either
container, so drag-out and cut-paste are the ordinary moves 13 calls
them, registering ordinary Move steps. The delete inverse moves the
card back to its captured lane and rank; redo replays the captured
trash rank, a value the gesture actually wrote; lane undo recreates
the subtree byte-faithfully in session. Purges register nothing —
where 13's trash section contradicts its own Rules on that, Rules
wins, filed for ruling. Staleness collapsed to present-or-absent: a
container is a path, so a foreign restore fails the delete step's
expectation structurally. Legacy tombstones migrate on the loose-file
tail hook, cards oldest-first so minting above top reproduces the
retired newest-first column, lanes returning live, one folded loss
row naming both directions. Put Back, restoreByDrag,
receiveRestoredCards, TrashEntry, and the kind machinery are deleted;
the trash column renders the container correctly with its full face
rework left to phase 3.

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

KanbanTests/WriterTestSupport.swift

@@ -93,6 +93,29 @@ struct WriterFixture {
     func entryNames(_ relativePath: String) throws -> [String] {
         try FileManager.default.contentsOfDirectory(atPath: url(relativePath).path).sorted()
     }
+
+    /// Moves a folder from one place in the board to another — a **foreign** move, the way an agent
+    /// or a hand-editor makes one: `FileManager` and nothing else, no `index.md` rewritten, no rank
+    /// touched. What the container-crossing rules are stated in terms of (02-architecture.md §
+    /// Live-reload resilience, resettled 2026-07-28).
+    func moveFolder(_ relativePath: String, to destinationPath: String) throws {
+        let destination = url(destinationPath)
+        try FileManager.default.createDirectory(
+            at: destination.deletingLastPathComponent(),
+            withIntermediateDirectories: true
+        )
+        try FileManager.default.moveItem(at: url(relativePath), to: destination)
+    }
+
+    /// A card folder moved into `<root>/.trash/` — the shape of a delete on disk, made foreignly.
+    func move(_ relativePath: String, toTrash cardName: String) throws {
+        try moveFolder(relativePath, to: ".trash/\(cardName)")
+    }
+
+    /// A card folder moved out of the trash into a lane — the shape of a restore, made foreignly.
+    func move(_ relativePath: String, toLane laneName: String, card cardName: String) throws {
+        try moveFolder(relativePath, to: "\(laneName)/\(cardName)")
+    }
 }
 
 // MARK: - Move/copy identities