Say what "open in container" is doing, and land on the pane doing it

Opening a page is a container probe, a browser launch, a page load and
often a viewer start — several seconds during which the only feedback
was the click itself. Worse from a terminal, where the result appears in
a pane the user is not looking at.

So: the backend emits progress on the existing `container-progress`
channel at each step, the Browser tab renders that line whenever it is
set — the progress belongs to the project, not to whoever pressed the
button, which is what lets a terminal-initiated open report anywhere at
all — and the terminal's "In container" now selects the project's
Browser tab before starting, so the line has somewhere to appear.

Selecting a sub-tab from outside needed a route: `ProjectHome` keeps it
in local state, so `openProjectHomeTab` parks a request in the store and
the pane consumes it once. Consumed once, so it cannot fight the user's
own clicking afterwards.

Preview releases now prune themselves to the newest KEEP_PREVIEWS (2),
in a job that runs only if all three platforms published — a
half-finished run must not evict a good older build. The cleanup
workflow's manual sweep stays as the backstop.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/src/store/appState.ts

@@ -71,6 +71,18 @@ interface AppState {
   tabOrder: string[];
   activeTabKey: string | null;
   openProjectHome: (projectId: string) => void;
+  /**
+   * Open a project's home tab *on a particular sub-tab*.
+   *
+   * The sub-tab is local state inside `ProjectHome`, so this parks a request
+   * here for it to pick up: an action taken somewhere else entirely — opening a
+   * page in the container's browser from a terminal — has to be able to land
+   * the user on the pane that shows the result.
+   */
+  openProjectHomeTab: (projectId: string, tab: string) => void;
+  /** Consumed once by `ProjectHome`, then cleared. */
+  pendingHomeTab: { projectId: string; tab: string } | null;
+  clearPendingHomeTab: () => void;
   closeHomeTab: (projectId: string) => void;
   setActiveTabKey: (key: string) => void;
   cycleTab: (delta: number) => void;
@@ -235,6 +247,20 @@ export const useAppState = create<AppState>((set) => ({
         ...activation(key),
       };
     }),
+  openProjectHomeTab: (projectId, tab) =>
+    set((state) => {
+      const key = homeTabKey(projectId);
+      return {
+        selectedProjectId: projectId,
+        tabOrder: state.tabOrder.includes(key)
+          ? state.tabOrder
+          : [...state.tabOrder, key],
+        pendingHomeTab: { projectId, tab },
+        ...activation(key),
+      };
+    }),
+  pendingHomeTab: null,
+  clearPendingHomeTab: () => set({ pendingHomeTab: null }),
   closeHomeTab: (projectId) =>
     set((state) => {
       const key = homeTabKey(projectId);