feat(scope): maintain variable tables by data type namespace (#84)

[Dev10-sys]

Implements Issue #84 by introducing data-type namespaced variable tables
for global, process, and routine scopes.

Changes

• Added:

  • _globalVariableTable[dataType][variable]
  • _processVariableTable[process][dataType][variable]
  • _routineVariableTable[routine][dataType][variable]

• Implemented:

  • addGlobalVariable / getGlobalVariable(variable, dataType?)
  • addProcessVariable / getProcessVariable(variable, process, dataType?)
  • addRoutineVariable / getRoutineVariable(variable, routine, dataType?)

• Improved query logic:

  • With dataType → strict namespace lookup
  • Without dataType → throws AmbiguousVariableError if multiple matches exist
  • Avoided Object.values() allocation in hot path

• Reset clears new variable tables

• Exported new APIs via scope module and package entrypoint

Testing

All existing tests pass.
TypeScript check clean.
No changes to existing SymbolTableStack behavior.