portal: 90% threshold for budget notices; sweep 3x a day

Trigger becomes proportional (90% of the balance used) instead of a $2 floor, so a member on $15 and one on $35 are treated the same. The once-per-crossing latch keys on the same fraction. membership_sweep moves from '0 3 * * *' to '0 3,11,19 * * *' so the notice arrives within hours of crossing rather than up to a day later. BUDGET_NOTICES remains off.

CloudronManifest.json

@@ -15,7 +15,7 @@
   "sendmail": {},
   "scheduler": {
    "membership_sweep": {
-    "schedule": "0 3 * * *",
+    "schedule": "0 3,11,19 * * *",
     "command": "/app/code/sweep.sh"
    },
    "rag_refresh": {