feat: Thinking indicator + cancel button in the app

- Bridge: _emit_activity() spiegelt OpenClaw agent events als agent_activity
  an RVS, dedupliziert State-Wechsel. chat:final/error senden idle.
- Bridge: Neuer cancel_request-Handler ruft Diagnostic /api/cancel per HTTP.
- Diagnostic: Neuer POST /api/cancel Endpoint (gleiche Logik wie WS-Cancel).
- RVS: agent_activity + cancel_request in ALLOWED_TYPES.
- App: Gelber Indicator ueber der Input-Bar mit Text je nach Activity,
  roter Abbrechen-Button. Cancel sendet cancel_request via RVS.
- issue.md: Erledigte Bugfixes + Features konsolidiert.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

diagnostic/server.js

@@ -1143,6 +1143,16 @@ const server = http.createServer((req, res) => {
   } else if (req.url === "/api/session") {
     res.writeHead(200, { "Content-Type": "application/json" });
     res.end(JSON.stringify({ sessionKey: activeSessionKey }));
+  } else if (req.url === "/api/cancel" && req.method === "POST") {
+    log("warn", "server", "HTTP /api/cancel — Cancel-Request (von Bridge)");
+    pendingMessageTime = 0;
+    watchdogWarned = false;
+    watchdogFixAttempted = false;
+    if (pipelineActive) pipelineEnd(false, "Vom Benutzer abgebrochen (App)");
+    else broadcast({ type: "agent_activity", activity: "idle" });
+    dockerExec("aria-core", "openclaw doctor --fix 2>/dev/null || true").catch(() => {});
+    res.writeHead(200, { "Content-Type": "application/json" });
+    res.end(JSON.stringify({ ok: true }));
   } else if (req.url.startsWith("/shared/")) {
     // Dateien aus Shared Volume ausliefern (Bilder, Uploads)
     const filePath = decodeURIComponent(req.url);