Build the template chooser and Save as Template

The chooser completes its three tiers: bundled by template order, then
keyed user templates, then keyless boards by display name — and a
malformed user template still lists, by folder name with the loader's
own sentence on the row, never failing its neighbours. The store is
re-scanned on every presentation and on app activation, the Reveal
round trip made honest without watching a folder 09 deliberately
leaves unwatched; Reveal lives in the chooser's header and mints the
store on first press. Save as Template repeats Duplicate's sequence —
progress row with Cancel, flush, detached cancellable copy — through
the engine: mint the store, read the next user order before the copy
can count itself, Finder-ladder the name, copy excluding .git and
.trash/, then stamp the whole template: mapping on the landed copy
through updateIndex, with no bracket because the copy lives outside
every watched board. Folder attributes deliberately don't carry — the
one lock the command stays live under is the read-only-DMG one, and
carrying its mode bits would mint a read-only template in the user's
own store; the command gates instead on the real hazard, unsaved card
content. A signpost names the template only when the ladder renamed
it. One name ladder now serves Duplicate and the store.

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

Kanban/App/AppModel.swift

@@ -710,6 +710,22 @@ public final class AppModel {
         await coordinator(for: ref).flushPendingWork()
     }
 
+    /// Whether any of this board's card windows is holding content the files do not have — a dirty
+    /// Edit buffer or a typed-in raw-source outlet (`CardSessionFlushing.holdsUnsavedContent`).
+    ///
+    /// **One caller, one rule**: File ▸ Save as Template's carve-out from the read-only lock. Under
+    /// the unwritable-location lock the item stays live — "reads the board, writes Application
+    /// Support" — but only while no such session exists, because the lock has suspended exactly the
+    /// saves that would flush one and 09-templates.md's never-misses-keystrokes guarantee outranks
+    /// the item's availability (02-architecture.md ▸ Live-reload resilience, settled scoping).
+    ///
+    /// It asks the sessions rather than the store: the content in question is in *memory*, in the
+    /// card windows, which is the whole reason the flush cannot reach it.
+    public func hasUnsavedCardContent(for ref: BoardWindowRef) -> Bool {
+        guard let session = sessions[ref] else { return false }
+        return session.cardRefs.contains { cardSessions[$0]?.holdsUnsavedContent == true }
+    }
+
     /// Quit: the same sequence, once per open board, **sequentially**.
     ///
     /// Sequential rather than concurrent so each board's ordering is the one 02 fixes rather than