Give the registry live display-state write-through and record-before-load

BoardRecord carries icon/iconColor; recordOpen/recordClose stamp them with the
display name, and a displayStateDelegate on the store (wired in BoardWindowHost
beside onFrameChanged) syncs all three through BoardRegistry.syncDisplayState on
every successful reload — welcome rows now wear the board's own icon and follow
in-app renames live. recordOpen now runs before the load with the folder name as
a brand-new record's provisional display name, so a first open that fails
fail-fast still lands in recents carrying the failure row-level (02's rule); an
existing record's cached name survives a failing retry, and the welcome fallback
list remains only for failures naming no record at all.

Claude-Session: https://claude.ai/code/session_01CqjXB7ASoWtbyoGod68k97

KanbanTests/WelcomeRowTests.swift

@@ -23,7 +23,9 @@ private func record(
     at path: String,
     lanes: Int? = nil,
     cards: Int? = nil,
-    opened: Date = Date()
+    opened: Date = Date(),
+    icon: String? = nil,
+    iconColor: String? = nil
 ) -> BoardRecord {
     BoardRecord(
         bookmark: Data(),
@@ -31,7 +33,9 @@ private func record(
         lastKnownPath: path,
         lastOpened: opened,
         laneCount: lanes,
-        cardCount: cards
+        cardCount: cards,
+        icon: icon,
+        iconColor: iconColor
     )
 }
 
@@ -208,6 +212,26 @@ struct WelcomeRowTests {
                 "the sort rule lives in BoardRegistry.recents() and must not be duplicated here")
     }
 
+    @Test("A record's cached icon and iconColor ride straight through to its row")
+    func iconAndIconColorPassThrough() throws {
+        let recent = available(record(name: "Roadmap", at: "/Boards/Roadmap.kanban", icon: "star.fill", iconColor: "fern"))
+
+        let row = try #require(WelcomeRow.derive(recents: [recent], failures: []).rows.first)
+
+        #expect(row.icon == "star.fill")
+        #expect(row.iconColor == "fern")
+    }
+
+    @Test("A record with no cached icon carries nil through to its row — the renderer's default to draw")
+    func noIconIsNilNotAGuess() throws {
+        let recent = available(record(name: "Roadmap", at: "/Boards/Roadmap.kanban"))
+
+        let row = try #require(WelcomeRow.derive(recents: [recent], failures: []).rows.first)
+
+        #expect(row.icon == nil)
+        #expect(row.iconColor == nil)
+    }
+
     @Test("A record with no display name falls back to its folder name, extension stripped")
     func displayNameFallsBackToTheFolderName() {
         let recent = available(record(name: "", at: "/Boards/Untitled.kanban"))