feat: Player Character flag + GM Finance Ledger

- Add isPlayerCharacter field to template.json (character.details)
- Bio tab: checkbox 'Player Character' bound to system.details.isPlayerCharacter
- SLAGMFinanceTool Application: GM-only window listing all PC-flagged
  actors with current balance, weekly income, weekly expenses, net
  weekly income, and a Calculate button per character
- Calculate button: applies netWeekly to credits (credits += net)
- Calculate All button: applies week to every listed PC at once
- Actor Directory: GM-only 'Finance Ledger' button opens the tool
- CSS: styled PC flag row and full GM Finance Ledger table
- Version bump: 1.4.5 → 1.4.6

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": "1.4.5",
+  "version": "1.4.6",
   "compatibility": {
     "minimum": 13,
     "verified": "14.359"