Clarify reserved cash currency labels

[Pigbibi]

Summary

• show the minimum reserved cash input with USD/HKD based on account config or selected strategy domain
• allow account config to declare cash_currency / market_currency / trading_currency
• document reserved-cash overrides as selected-account-currency amounts

Tests

• node --experimental-default-type=module tests/strategy_switch_worker_validation.mjs
• python3 -m pytest tests/test_runtime_settings.py -q
• node --check --input-type=module < web/strategy-switch-console/worker.js
• node --check --input-type=module < web/strategy-switch-console/page_asset.js
• node --check --input-type=module < web/strategy-switch-console/strategy_profiles_asset.js
• sed -n '/<script>/,/</script>/p' web/strategy-switch-console/index.html | sed '1d;' | node --check --input-type=commonjs
• jq empty web/strategy-switch-console/account-options.example.json web/strategy-switch-console/strategy-profiles.example.json
• git diff --check