fix(oracle-l8-r3): wizard 'Manual review' + chat cold-start seed

Close Oracle's two standing caveats so they can't gate a future loop:

1. Wizard dispatch label 'Person' was vague (Oracle: could imply chat
   recipient, not work-routing). Now 'Manual review' in both dropdown
   and preview-pane badge. dispatch_kind storage value unchanged
   ('human'/'agent'/'system' for EA2).

2. Chat unread cold-start. Topbar badge depended entirely on
   localStorage being populated by Chat scene's first visit. Fresh
   browser / private window / cleared storage saw 0 unread until then.
   Added seedHeadsIfMissing in App.tsx topbar poll: on first refresh
   (and only when localStorage heads count < thread count), fetches
   last message per thread ONCE and persists to localStorage. Subsequent
   ticks reuse the cache — same idle-poll budget (test still PASS).

src/scenes/Wizard.tsx

@@ -281,7 +281,7 @@ export default function Wizard() {
                 <li key={n._key || i} className="wizard-preview-chain-item">
                   <span className="wizard-preview-chain-idx">{i + 1}</span>
                   <span className="wizard-preview-chain-name">{n.display_name || "Untitled step"}</span>
-                  <span className={`wizard-preview-chain-kind kind-${n.dispatch_kind || "human"}`}>{({ human: "Person", agent: "Assistant", system: "System" } as Record<string, string>)[n.dispatch_kind || "human"] || "Person"}</span>
+                  <span className={`wizard-preview-chain-kind kind-${n.dispatch_kind || "human"}`}>{({ human: "Manual review", agent: "Assistant", system: "System" } as Record<string, string>)[n.dispatch_kind || "human"] || "Manual review"}</span>
                 </li>
               ))}
             </ol>
@@ -412,7 +412,7 @@ export default function Wizard() {
                           updateDraft({ nodes: newNodes });
                         }}
                       >
-                        <option value="human">Person</option>
+                        <option value="human">Manual review</option>
                         <option value="agent">Assistant</option>
                         <option value="system">System</option>
                       </select>