fix(ui): zone writes during startup no longer erase persisted Workboard pins (#123475)

The reconciler dropped workboard entries from the canonical persisted list
whenever workboardEnabled was false — but enablement reads as disabled until
the runtime config snapshot loads, so any pin/unpin/drag in that window
permanently deleted every workboard pin from synced prefs. The boards-not-
ready branch already preserved slots for exactly this ambiguity; disabled
now folds into it. Prod net −1.

ui/src/lib/sidebar-zone.test.ts

@@ -64,7 +64,7 @@ describe("reconcileSidebarZone", () => {
     ).toEqual(["route:usage"]);
   });
 
-  it("keeps active Workboard boards and drops stale or plugin-off pins", () => {
+  it("keeps active Workboard boards, drops stale ids, and preserves plugin-off pins", () => {
     const boards = [
       { id: "default", total: 0, active: 0, archived: 0, byStatus: {} },
       { id: "ops", total: 0, active: 0, archived: 0, byStatus: {} },
@@ -80,6 +80,8 @@ describe("reconcileSidebarZone", () => {
         true,
       ).sidebarEntries,
     ).toEqual(["workboard:ops", "route:usage"]);
+    // Disabled is indistinguishable from an unloaded config snapshot at
+    // startup; a zone write then must not erase persisted pins.
     expect(
       reconcileSidebarZone(
         ["workboard:ops", "route:usage"],
@@ -89,8 +91,11 @@ describe("reconcileSidebarZone", () => {
         boards,
         false,
         true,
-      ).sidebarEntries,
-    ).toEqual(["route:usage"]);
+      ),
+    ).toEqual({
+      entries: [{ type: "route", route: "usage" }],
+      sidebarEntries: ["workboard:ops", "route:usage"],
+    });
   });
 
   it("preserves Workboard pins until the active plugin's board catalog is authoritative", () => {

ui/src/lib/sidebar-zone.ts

@@ -51,14 +51,13 @@ export function reconcileSidebarZone(
       continue;
     }
     if (entry.type === "workboard") {
-      if (!workboardEnabled) {
-        continue;
-      }
       seen.add(canonicalKey);
       canonical.push(canonicalKey);
-      // An unloaded catalog cannot distinguish deletion from startup. Preserve
-      // the slot but render nothing until the active plugin returns its ids.
-      if (!workboardBoardsReady) {
+      // Disabled reads exactly like startup: the runtime config snapshot is
+      // unloaded until the gateway answers, so a zone write in that window
+      // would erase every persisted pin. Preserve the slot, render nothing;
+      // only a loaded catalog that positively lacks the id deletes below.
+      if (!workboardEnabled || !workboardBoardsReady) {
         continue;
       }
       if (!validBoardIds.has(entry.boardId)) {