fix: rewrite GM Finance Ledger

- Read credits via actor._source (raw DB) to bypass DataModel
- Read all finance fields via _readFinance() using same approach
- Calculate now zeros ALL income + expense fields after applying
  (salary, bpnReward, other income, accommodation, drugs, subs,
   other expense, bulletTax, ammoSpentSession, debt)
- Auto-refresh ledger via updateActor hook whenever any actor updates
- Ledger now reflects live sheet values immediately

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": "1.4.8",
+  "version": "1.4.9",
   "compatibility": {
     "minimum": 13,
     "verified": "14.359"