fix(postgres): give probes room on an I/O-bound single node

pg_isready with the 1s default times out under I/O stall and kubelet kills a healthy postgres mid-recovery; each kill restarts a multi-minute fsync from zero and loops forever. readiness/liveness timeout 5s, liveness threshold 5, startup budget 15min.

postgres/k8s/postgres.yaml

@@ -60,16 +60,26 @@ spec:
               command: ["pg_isready", "-U", "postgres", "-d", "postgres"]
             initialDelaySeconds: 10
             periodSeconds: 10
+            # Generous timeout: on an I/O-bound single node even exec can take
+            # seconds, and a 1s default kills a healthy postgres mid-recovery.
+            timeoutSeconds: 5
           startupProbe:
             exec:
               command: ["pg_isready", "-U", "postgres", "-d", "postgres"]
-            failureThreshold: 30
+            # Crash recovery on an I/O-starved single node can fsync for 10+
+            # minutes; killing postgres mid-recovery restarts the fsync from
+            # zero and loops forever. 90x10s = 15 minutes of grace.
+            failureThreshold: 90
             periodSeconds: 10
           livenessProbe:
             exec:
               command: ["pg_isready", "-U", "postgres", "-d", "postgres"]
             initialDelaySeconds: 30
             periodSeconds: 20
+            # Same I/O reasoning as readiness, plus more misses before a kill:
+            # restarting postgres on a loaded node only makes recovery longer.
+            timeoutSeconds: 5
+            failureThreshold: 5
           resources:
             requests:
               memory: "512Mi"