Add JUnit 5 unit tests for core DayTrader classes

[alexlang74]

Summary

This PR introduces a comprehensive JUnit 5 unit test suite for the most important classes in the DayTrader 8 application. The project had no automated tests before this change.

Changes

pom.xml

• Added junit-jupiter 5.10.1 (test scope)
• Added javax.json 1.1.4 Glassfish reference implementation (test scope, required for MarketSummaryDataBean.toJSON())
• Added maven-surefire-plugin 3.1.2 to enable the JUnit 5 platform runner

New test files (src/test/java/)

Entity beans

Test class	Tests	What's covered
AccountDataBeanTest	17	Constructors, login()/logout(), equals/hashCode, toString/toHTML, random instance
AccountProfileDataBeanTest	12	Constructors, all accessor setters/getters, equals/hashCode, random instance
HoldingDataBeanTest	14	Constructors, getQuoteID() delegation to QuoteDataBean, equals/hashCode, random instance
OrderDataBeanTest	26	isBuy/isSell/isOpen/isCompleted/isCancelled, cancel(), symbol delegation, equals/hashCode
QuoteDataBeanTest	12	All field accessors, equals/hashCode, random instance

Utility classes

Test class	Tests	What's covered
FinancialUtilsTest	17	computeGain, computeGainPercent (including zero open balance), computeHoldingsTotal (null/empty/populated), HTML formatters
TradeConfigTest	47	Runtime modes, order processing modes, MAX_USERS/QUOTES/HOLDINGS, order fees, all random generators, setConfigParam, constants
KeyBlockTest	16	size(), sequential forward iteration, hasPrevious/previous, nextIndex, unsupported operations
TimerStatTest	13	Default state, setters/getters, ms-to-seconds conversions, average computation

Data beans

Test class	Tests	What's covered
MarketSummaryDataBeanTest	12	Constructor, lazy gainPercent caching, toJSON() keys, toString/toHTML with and without collections, random instance
RunStatsDataBeanTest	16	All counter setters/getters (12 fields), toString output

Total: 202 tests — all passing.

Test selection rationale

Classes were selected based on: (1) centrality to the trading domain (entity beans used across all layers), (2) pure business logic with no container/EJB dependencies (making them straightforwardly unit-testable), and (3) non-trivial behaviour worth guarding (financial calculations, state machines in OrderDataBean, key iteration in KeyBlock, configuration management in TradeConfig).