Balance-tax bracket keys are decimals in shipped config.yml → silently ignored (Treasury + Business)

Found during the economy-explorer docs accuracy sweep; confirmed by a live Paper YamlConfiguration probe.

Problem: Both shipped configs define the balance-tax brackets with DECIMAL keys:

• treasury/src/main/resources/config.yml:67-72 (0.00, 100000.00, 200000.00, 300000.00, 500000.00)
• business/src/main/resources/config.yml:34-39 (same)

BalanceTaxConfiguration.load() reads the bracket section via getConfigurationSection("tax.balance.brackets").getKeys(false) then new BigDecimal(key) / getString(key). Snakeyaml/Bukkit parses a decimal-looking key like 100000.00 as a NESTED path (100000 → section → 00), so getKeys(false) returns [0, 100000, 200000, ...] as sections, getString(key) is null, and every bracket is skipped — the map falls back to the hardcoded DEFAULT_BRACKETS.

Why it's currently invisible: DEFAULT_BRACKETS has the same values as the shipped config, so effective taxation is correct. But any admin who edits these bracket values is silently ignored — the documented config doesn't work. (Both economy-explorer config docs already WARN that keys must be integers; the shipped configs violate that warning.)

Fix options: (a) ship integer keys (100000: etc.) in both config.yml files — matches the docs and makes edits take effect; and/or (b) make the loader tolerant: read the bracket section as a flat map / accept decimal-string keys. Recommend (a) at minimum, in both treasury and business (shared pattern). Add a test that a non-default bracket edit actually changes the computed tax.

Components: Treasury and Business (same bug in both).