Migrate the FX (Functional eXtensions) testing framework to a modern
JUnit 5 Model-Based Testing (MBT) framework.

New Features:
- Core MBT Framework:
  - Model: Base class for state machine models with reflection-based discovery
  - ModelEngine: Executes state machine exploration with reproducible seeds
  - @ModelAction: Annotation for marking state transition methods
  - @ModelRequirement: Annotation for defining preconditions
  - @ModelVariable: Annotation for tracking state variables
  - ModelEngineOptions: Configuration for timeout, maxActions, weightSchemes
  - WeightScheme: Multiple action selection strategies (flat, weighted, etc.)

- Connection Testing:
  - ConnectionModel: State machine for java.sql.Connection (equiv. to fxConnection)
  - ConnectionModelTest: JUnit 5 tests (equiv. to connection.java)
  - ConnectionProperty: Property definitions for connection strings
  - SqlServerDriverProperties: Driver property catalog (equiv. to fxSqlServerDriver)

- JUnit 5 Integration:
  - @modeltest: Declarative test configuration annotation
  - ModelTestExtension: JUnit 5 extension for automatic seed handling

Key Benefits:
- Seed-based reproducibility: Failed tests can be reproduced exactly
- Auto-exploration: Discovers edge cases through state machine traversal

Replace complex Model-Based Testing framework with simplified
StateMachineTest approach for better maintainability.

Removed (14 files):
- mbt/core/: Model, ModelEngine, ModelAction, ModelRequirement,
  ModelVariable, ModelEngineOptions, WeightScheme, ModelTest,
  ModelTestExtension, ModelRequirements
- mbt/connection/: ConnectionModel, ConnectionModelTest,
  ConnectionProperty, SqlServerDriverProperties

Added (2 files):
- statemachinetest/core/StateMachineTest.java
- statemachinetest/resultset/ResultSetStateTest.java

Key simplifications:
- Single base class instead of multiple annotations
- Built-in state tracking without complex reflection
- Seed-based reproducibility preserved
- Cleaner API for writing state machine tests

Add comprehensive Transaction State Machine tests covering FX framework scenarios:

Transaction Operations:
- Basic transaction control (setAutoCommit, commit, rollback)
- Savepoint operations (setSavepoint, rollback to savepoint, releaseSavepoint)
- Transaction isolation level testing (READ_UNCOMMITTED to SERIALIZABLE)
- Real database transaction tests with commit/rollback verification

FX Missing Test Coverage:
- testCommitTransaction - Basic transaction commit
- testRollbackTransaction - Basic transaction rollback
- testRollbackTransactionOnCnClose - Implicit rollback on connection close
- testRollbackTransactionOnPoolCnClose - Pool connection rollback simulation

XA Transaction Tests (simulated):
- testTransactionAfterPrepare - XA two-phase commit prepare
- testCaseCleanMultipleSuspend_Join - XA suspend/resume (TMSUSPEND/TMJOIN)
- testCaseClean - XA cleanup and recovery
- testXATimeout - XA transaction timeout handling

Connection Operations:
- Statement creation (createStatement, prepareStatement, prepareCall)
- Connection configuration (holdability, catalog, warnings)
- DatabaseMetaData retrieval

…bility

- Remove all simulated test cases, keep only real JDBC database tests
- Add seeded Random support via sm.getRandom() for full reproducibility
- Engine now sets seeded Random on StateMachineTest before execution
- Update RealExecuteUpdateAction and RealAbsoluteAction to use shared RNG
- Fix getValidActions() to log exceptions instead of silently dropping actions
- Add onValidRow state tracking for ResultSet cursor position
- Tighten RealGetStringAction.canRun() to only allow when on valid row
- Remove try-catch from RealGetStringAction to let exceptions propagate

- Make ResultSetStateTest and TransactionStateTest public for consistency
- Add maxActions validation (n >= 1) with IllegalArgumentException
- Handle total=0 case in weighted selection with uniform random fallback
- Fix printf format issue for state map (avoid % interpretation)
- Improve error message to show exception type, handle null message, print stack trace

Co-authored-by: David Engel <[email protected]>