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/CardAttachmentsTests.swift

@@ -191,13 +191,12 @@ struct RemoveAttachmentStoreTests {
         try fixture.file("\(Ident.lane1)/\(Ident.card1)/attachments/shot.png", Data([0x02]))
         let store = try BoardStore(rootURL: fixture.root)
 
-        store.removeAttachment(named: "shot.png", fromCard: card2)                             // tombstoned
+        store.removeAttachment(named: "shot.png", fromCard: ItemID(rawValue: Ident.lane2))      // a lane
         store.removeAttachment(named: "shot.png", fromCard: ItemID(rawValue: Ident.indexless))  // no such card
         store.removeAttachment(named: "shot.png", fromCard: lane1)                              // a lane
         store.removeAttachment(named: "", fromCard: card1)                                      // no name
 
         #expect(try fixture.entryNames("\(Ident.lane1)/\(Ident.card1)/attachments") == ["shot.png"])
-        #expect(try fixture.entryNames("\(Ident.lane1)/\(Ident.card2)/attachments") == ["shot.png"])
         #expect(store.banners.oneShots.isEmpty, "a vanished target is a silent no-op, not a failure")
     }