Three bugs:
1. weeklyExpenses total omitted bulletTax from the sum (both getData paths)
Fix: add (_exp.bulletTax||0) to the calculation
2. _applyBulletTax read undefined credits as 0 (actors created before the
credits field existed have null/undefined, not zero)
Fix: fallback to 500 (template default) only when value is null/undefined
3. Finances tab CURRENT BALANCE showed just C because input had no placeholder
Fix: add placeholder=500 min=0 to the credits input in character-sheet.hbs