fix: bullet tax doubled + full caliber catalog + fix undefined/undefined (v1.4.3)

Bullet tax rules (per user spec):
- Tax is now 2x base round cost on every shot (ammo cost + levy)
- e.g. 7mm standard = 10c/round -> 20c charged per round fired
- Applied immediately on ATTACK press, not deferred to REST
- Weapon locking still only on push + bane (unchanged)

Ammo catalog expanded (was missing 9 calibers -> 0 tax for those weapons):
- .44 (Revolver): 8/24/45c standard/AP/HE
- .454 (Heavy Pistol): 10/28/50c
- .50 (Heavy Pistol): 12/35/60c
- 3mm (Machine Pistol): 3/9/20c
- 7mm (SLA Carbine/LMG): 10/28/55c
- 8mm (Sniper Rifle): 14/40/75c
- 12g (Shotgun): 18/45/80c
- 40mm (Grenade/Launcher): 80/180/140c
- Rail (Rail Gun): 50/120/200c

SLA_WEAPON_DEFAULT_CALIBER expanded to cover all weapon types

Chat display: removed undefined/undefined (Remaining X/Y) - weapons are
always assumed loaded; display now shows Rounds fired + tax cost only

Tax notification updated to show 2x calculation clearly

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": "1.4.2",
+  "version": "1.4.3",
   "compatibility": {
     "minimum": 13,
     "verified": "14.359"