Realign code with the 2026-07-29 findings-resolution rulings

Nine rulings land as code. Reorders don't stamp — one container-change
predicate (WriteOperation.rewritesOrderOnly): within-container reorders
and the renumber rescale rewrite only order, while cross-lane, cross-board,
and trash moves stamp modified and clear modified-by; no trash special
case exists, and the m8 undo inverses conform through the same seam.
Copies are transactions: the root-strict/nested-lenient split retires for
a whole-subtree stampability preflight that refuses loudly naming the
offender, and every item-level copy severs remote/remote-state at every
level (whole-board forks carry them verbatim). Paste refuses, never
degrades: the embedded-index.md materialization and its loss row retire;
a missing staged snapshot produces nothing and posts an error-tone
one-shot named from manifest metadata. Coerce-tier fallbacks log through
the Defect stream with path context attached loader-side. Displacement is
level-uniform: a file squatting attachments inside a card heals by the
same rename ladder as board-root squatters; comments stays tolerated.
Delete Immediately joins card and lane context menus as Delete's
⌥-alternate with its own VO custom action, routed through an explicit
container so the menu target outranks standing selection. Agent guide v7
teaches the stamp discipline and the card-level attachments claim, and
sheds two stale v6 lines (lanes trash now; kind is taught). Verified
conformant, unchanged: edition-aware Undo/Redo disable, trash marquee
full-height backdrop.

Both schemes 1854 tests / 318 suites green; verify-editions 30/30.

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

KanbanTests/WriterTestSupport.swift

@@ -211,6 +211,27 @@ enum Item {
     /// A whole-frontmatter flow mapping carrying a `modified-by`: readable, uneditable, and so
     /// left byte-verbatim by a copy — stale attribution included.
     static let uneditable = "---\n{schema: 1, order: 1024, title: Odd, modified-by: claude}\n---\nodd body\n"
+
+    /// An item carrying one of the **reserved tracker keys** — `remote` on a board or card,
+    /// `remote-state` on a lane (01-storage-format.md § Enhanced schema) — beside an ordinary unknown
+    /// key, so a copy's tracker sever can be told apart from unknown-key preservation breaking.
+    ///
+    /// Nothing in this version reads the keys; what the suites pin is that an **item-level copy drops
+    /// them** (ruled 2026-07-29) while a whole-board fork carries them verbatim.
+    static func tracked(order: String, title: String, key: String) -> String {
+        """
+        ---
+        schema: 1
+        title: \(title)
+        order: \(order)
+        project: lanework       # agent overlay
+        \(key): gitea#42
+        created: 2026-01-01T09:00:00Z
+        ---
+        \(title) body.
+
+        """
+    }
 }
 
 // MARK: - Failure assertion