Open saved session: visible progress + clear errors (no silent no-op)

The status line only rendered inside the last-in-memory-session block, so 'Open
saved session' processed invisibly — looked like nothing happened. Now: the
transcript status (with a spinner) is always shown, the processing(0,0) reconcile
phase reads 'Working… (this can take a few minutes)', and invalid picks surface an
alert (not a recorded session / already processing / unreadable transcript) instead
of doing nothing.

Ten31Transcripts/UI/MenuBarView.swift

@@ -99,14 +99,19 @@ struct MenuBarView: View {
                     }
                     Spacer()
                 }
-                if !transcriptText.isEmpty {
-                    Text(transcriptText).font(.caption).foregroundStyle(transcriptColor)
-                }
             }
 
-            Button("Open saved session…") { session.openSavedSession() }
-                .buttonStyle(.link).font(.caption)
-                .disabled(transcriptProcessing)
+            HStack(spacing: 6) {
+                Button("Open saved session…") { session.openSavedSession() }
+                    .buttonStyle(.link).font(.caption)
+                    .disabled(transcriptProcessing)
+                if transcriptProcessing { ProgressView().controlSize(.small) }
+            }
+
+            // Always-visible status (covers "Send to backend" AND "Open saved session").
+            if !transcriptText.isEmpty {
+                Text(transcriptText).font(.caption).foregroundStyle(transcriptColor)
+            }
         }
     }
 
@@ -152,6 +157,7 @@ struct MenuBarView: View {
     private var transcriptText: String {
         switch session.transcriptStatus {
         case .idle:                       return ""
+        case .processing(_, let t) where t == 0: return "Working… (this can take a few minutes)"
         case .processing(let d, let t):   return "Transcribing… chunk \(d)/\(t)"
         case .done(let s, let seg):       return "Transcript ready · \(s) speakers · \(seg) segments"
         case .failed(let m):              return "Transcript failed: \(m)"