The card window's ⌘V drops its picture branch — the attachments header now offers one instead

Raw image data on a card window's ⌘V was a keyboard shortcut with no visible
trigger; the sidebar's Attachments header now grows a quiet control — beside
the existing add affordance, present only while the pasteboard holds a
picture this card could take — that pastes it through the exact seam the
retired branch used (ClipboardStore.pasteImage(intoCard:in:), the board's
"Paste Image into Card" row's own call). The file-URL branch stays on ⌘V; a
Finder copy is still unambiguous. CardBodyTextView's paste-yield mechanism
needed no change at all — it forwards by capability, not by picture-specific
logic, so a screenshot ⌘V with the body editor focused is now a genuine
no-op there, served by the new control instead.

The pasteboard's re-read gains a fourth checkpoint — a window becoming key —
alongside menu-tracking, ⌘-down and app activation: a persistent visible
control has to read true continuously while its window is frontmost, not
only at the instant a menu or chord probes it.

Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy

KanbanTests/CardAttachmentsTests.swift

@@ -66,6 +66,19 @@ private func purgeFromTrash(_ url: URL?) -> Bool {
     return true
 }
 
+/// A `ClipboardStore` for the tests below that only need to satisfy `configureAttachments`'s
+/// paste-image seam — the affordance itself is `PasteImageTests`' subject, not this file's. A
+/// `FakePasteboard` (`ClipboardTests.swift`'s double, never the machine's) and a throwaway staging
+/// directory the caller tears down alongside its board fixture.
+@MainActor
+private func makeScratchClipboard() throws -> (clipboard: ClipboardStore, staging: URL) {
+    let staging = FileManager.default.temporaryDirectory
+        .appendingPathComponent("CardAttachmentsTests-\(UUID().uuidString)", isDirectory: true)
+    try FileManager.default.createDirectory(at: staging, withIntermediateDirectories: true)
+    let clipboard = ClipboardStore(pasteboard: FakePasteboard(), stagingRoot: staging, observesActivation: false)
+    return (clipboard, staging)
+}
+
 /// The same, by name, for the paths that do not hand the resulting URL back (the store's).
 @discardableResult
 private func purgeFromTrash(named name: String) -> Bool {
@@ -246,9 +259,13 @@ struct AddAttachmentTargetTests {
         defer { sources.tearDown() }
         let shot = try sources.file("shot.png", Data([0x89, 0x50]))
         let store = try BoardStore(rootURL: fixture.root)
+        let (clipboard, staging) = try makeScratchClipboard()
+        defer { try? FileManager.default.removeItem(at: staging) }
 
         let attachments = CardAttachments()
-        CardWindowHost.configureAttachments(attachments, store: store, cardID: card1, undo: CardWindowUndo())
+        CardWindowHost.configureAttachments(
+            attachments, store: store, cardID: card1, undo: CardWindowUndo(), clipboard: clipboard
+        )
         attachments.importFiles?([shot])
 
         #expect(try fixture.data("\(Ident.lane1)/\(Ident.card1)/attachments/shot.png") == Data([0x89, 0x50]))
@@ -264,9 +281,13 @@ struct AddAttachmentTargetTests {
         try fixture.file("\(Ident.lane1)/\(Ident.card1)/attachments/\(doomed)", Data([0x01]))
         try fixture.file("\(Ident.lane1)/\(Ident.card2)/attachments/\(doomed)", Data([0x02]))
         let store = try BoardStore(rootURL: fixture.root)
+        let (clipboard, staging) = try makeScratchClipboard()
+        defer { try? FileManager.default.removeItem(at: staging) }
 
         let attachments = CardAttachments()
-        CardWindowHost.configureAttachments(attachments, store: store, cardID: card1, undo: CardWindowUndo())
+        CardWindowHost.configureAttachments(
+            attachments, store: store, cardID: card1, undo: CardWindowUndo(), clipboard: clipboard
+        )
         attachments.removeFile?(doomed)
 
         #expect(try fixture.entryNames("\(Ident.lane1)/\(Ident.card1)/attachments").isEmpty)
@@ -283,9 +304,13 @@ struct AddAttachmentTargetTests {
         defer { fixture.tearDown() }
         try fixture.file("\(Ident.lane1)/\(Ident.card1)/attachments/shot.png", Data([0x01]))
         let store = try BoardStore(rootURL: fixture.root)
+        let (clipboard, staging) = try makeScratchClipboard()
+        defer { try? FileManager.default.removeItem(at: staging) }
 
         let attachments = CardAttachments()
-        CardWindowHost.configureAttachments(attachments, store: store, cardID: card1, undo: CardWindowUndo())
+        CardWindowHost.configureAttachments(
+            attachments, store: store, cardID: card1, undo: CardWindowUndo(), clipboard: clipboard
+        )
         attachments.cardFolder = cardFolder(fixture)
         attachments.names = ["shot.png"]