[Feature] Configurable starting gold amounts in Homebrew settings

Added `initialAmount` field to each currency type (coins, handfuls, bags, chests)
in the Homebrew settings schema. Defaults match book values (0, 1, 0, 0).

- Homebrew.mjs: added `initialAmount` NumberField per currency; `_initializeSource`
  coerces empty submissions to 0; `refreshConfig()` syncs values to
  `CONFIG.DH.RESOURCE.character.initialCurrency`
- resourceConfig.mjs: added mutable `initialCurrency` object on `character` export
- actorField.mjs: added `CharacterGoldField` subclass that reads initial values
  from config at actor creation time
- character.mjs: switched from `GoldField` to `CharacterGoldField`
- settings.hbs: restructured currency section to CSS Grid with column headers
  ("Quantity Name" / "Starting Amount") instead of per-field inline labels
- settings.less: added `.currency-rows` grid styles
- en.json: added `quantityName` and `initialAmount` localisation keys

module/config/resourceConfig.mjs

@@ -65,6 +65,7 @@ const companionBaseResources = Object.freeze({
 
 export const character = {
     base: characterBaseResources,
+    initialCurrency: { coins: 0, handfuls: 1, bags: 0, chests: 0 },
     custom: {}, // module stuff goes here
     all: { ...characterBaseResources }
 };