practice polish: no phantom wake, Practice header tag, honest meta

- needsContinuation: a persisted problem-pose ack (terminate:true ended
  the turn deliberately) owes no continuation — reloads after a pose no
  longer wake a phantom turn; error results stay owed like any
  interrupted tool.
- Chat header: practice sessions swap the phase chip for a quiet
  Practice tag (no probe→teach arc applies) and hide the coverage ring
  (practice never extracts — an ever-filling ring would lie).
- ChatSummary gains pendingProblem (activeProblemOf at projection); the
  sidebar meta says 'Problem waiting' for a practice row with a posed
  problem. Kind threads through Chat/[id] page.
- Home picker chip gains Clear (picks were otherwise irremovable).

app/chat/[id]/page.tsx

@@ -24,6 +24,7 @@ export default async function ChatPage({
 			key={chat.id}
 			chatId={chat.id}
 			title={chat.title}
+			kind={chat.kind ?? "teach"}
 			// Wave D: the record IS native agent history — the client view is
 				// derived app-side (core/view.ts projectView; GET serves the same
 				// native messages).