fix: prevent "852,500" corruption in Finance Ledger calculate

When actor.update() fires, Foundry auto-submits any open character
sheet form before re-rendering. If the sheet still showed the old
credits value (e.g. 500), that stale value raced the new one (852)
and got merged server-side into the corrupt string "852,500".

Fix: pass {render: false} to actor.update() so Foundry skips the
auto-submit entirely, then manually call app.render() on all open
sheets for that actor — they read fresh data and render cleanly.

system.json

@@ -2,7 +2,7 @@
   "id": "zero-engine",
   "title": "Zero Engine (SLA Industries)",
   "description": "A basic game system for SLA Industries using the Zero Engine rules.",
-  "version": "1.5.0",
+  "version": "1.5.1",
   "compatibility": {
     "minimum": 13,
     "verified": "14.359"