fix(ttsreader-kokoro): bump liveness probe timeouts (Sprint E Phase 1a)

Kokoro pod has 4 restarts in 2d6h with exit 143 (SIGTERM from kubelet).
kubectl describe events all show:

  Liveness probe failed: Get "http://10.42.229.109:8880/v1/audio/voices":
    context deadline exceeded

The probe path /v1/audio/voices shares the FastAPI worker pool with
/v1/audio/speech. A long synth (Bible chapter, 30+ sentences) holds the
pool past the prior 5s × 3 = 15s probe window, kubelet kills the pod,
in-flight renders fail. Operator hits "fallback chain failed" toasts +
partial-render breadcrumbs during these windows.

Bump probe timeoutSeconds 5 → 15 and failureThreshold 3 → 5 → 75 s of
grace before kubelet gives up. Combined with the kokoro-side circuit
breaker landing in TtsReader (Sprint E Phase 1b), the FC backend will
also stop slamming kokoro during recovery so it can serve the probe
even faster.

The companion Prometheus alerts (KokoroPodFlapping, PiperPodFlapping)
land in FlowerCore.Notes/scripts/monitoring/alerts.yml.

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

apps/fc-ttsreader/fc-ttsreader.yaml

@@ -296,14 +296,23 @@ spec:
             periodSeconds: 10
             timeoutSeconds: 5
             failureThreshold: 18
+          # Sprint E Phase 1a (kokoro stability) — 4 restarts in 2d6h with
+          # exit 143 traced to liveness probe `context deadline exceeded` while
+          # kokoro was busy synthesizing. /v1/audio/voices shares the FastAPI
+          # worker pool with /v1/audio/speech, so a long synth can starve the
+          # probe out within the prior 5s × 3 = 15s window. Bump timeoutSeconds
+          # 5 → 15 and failureThreshold 3 → 5 → 75s grace before kubelet kills
+          # the pod. The TtsCircuitBreaker on the synthesizer side (Phase 1b)
+          # backs this up so the FC backend stops slamming kokoro during
+          # recovery.
           livenessProbe:
             httpGet:
               path: /v1/audio/voices
               port: 8880
             initialDelaySeconds: 180
             periodSeconds: 30
-            timeoutSeconds: 5
+            timeoutSeconds: 15
-            failureThreshold: 3
+            failureThreshold: 5
 ---
 # fc-biblical-tts — eSpeak-NG-backed Ancient Greek + Hebrew TTS with
 # word-level timing for read-along playback. Companion to ttsreader-kokoro