refactor: Major reorganization of optimization_engine module structure

BREAKING CHANGE: Module paths have been reorganized for better maintainability.
Backwards compatibility aliases with deprecation warnings are provided.

New Structure:
- core/           - Optimization runners (runner, intelligent_optimizer, etc.)
- processors/     - Data processing
  - surrogates/   - Neural network surrogates
- nx/             - NX/Nastran integration (solver, updater, session_manager)
- study/          - Study management (creator, wizard, state, reset)
- reporting/      - Reports and analysis (visualizer, report_generator)
- config/         - Configuration management (manager, builder)
- utils/          - Utilities (logger, auto_doc, etc.)
- future/         - Research/experimental code

Migration:
- ~200 import changes across 125 files
- All __init__.py files use lazy loading to avoid circular imports
- Backwards compatibility layer supports old import paths with warnings
- All existing functionality preserved

To migrate existing code:
  OLD: from optimization_engine.nx_solver import NXSolver
  NEW: from optimization_engine.nx.solver import NXSolver

  OLD: from optimization_engine.runner import OptimizationRunner
  NEW: from optimization_engine.core.runner import OptimizationRunner

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

optimization_engine/nx/import_expressions.py

@@ -0,0 +1,82 @@
+"""
+NX Journal: Import expressions from .exp file
+
+Usage: run_journal.exe import_expressions.py -args <prt_file> <exp_file>
+"""
+import sys
+import NXOpen
+
+
+def main(args):
+    if len(args) < 2:
+        print("[ERROR] Usage: import_expressions.py <prt_file> <exp_file>")
+        sys.exit(1)
+
+    prt_file = args[0]
+    exp_file = args[1]
+
+    theSession = NXOpen.Session.GetSession()
+
+    # Open the part file
+    partLoadStatus1 = None
+    try:
+        workPart, partLoadStatus1 = theSession.Parts.OpenActiveDisplay(
+            prt_file,
+            NXOpen.DisplayPartOption.AllowAdditional
+        )
+    finally:
+        if partLoadStatus1:
+            partLoadStatus1.Dispose()
+
+    print(f"[JOURNAL] Opened part: {prt_file}")
+
+    # Import expressions from .exp file
+    markId1 = theSession.SetUndoMark(NXOpen.Session.MarkVisibility.Visible, "Import Expressions")
+
+    try:
+        expModified, errorMessages = workPart.Expressions.ImportFromFile(
+            exp_file,
+            NXOpen.ExpressionCollection.ImportMode.Replace
+        )
+
+        print(f"[JOURNAL] Imported expressions from: {exp_file}")
+
+        # expModified can be either a bool or an array depending on NX version
+        if isinstance(expModified, bool):
+            print(f"[JOURNAL] Import completed: {expModified}")
+        else:
+            print(f"[JOURNAL] Expressions modified: {len(expModified)}")
+
+        if errorMessages:
+            print(f"[JOURNAL] Import errors: {errorMessages}")
+
+        # Update the part to apply expression changes
+        markId2 = theSession.SetUndoMark(NXOpen.Session.MarkVisibility.Invisible, "NX update")
+        nErrs = theSession.UpdateManager.DoUpdate(markId2)
+        theSession.DeleteUndoMark(markId2, "NX update")
+
+        print(f"[JOURNAL] Part updated (errors: {nErrs})")
+
+        # Save the part
+        partSaveStatus = workPart.Save(
+            NXOpen.BasePart.SaveComponents.TrueValue,
+            NXOpen.BasePart.CloseAfterSave.FalseValue
+        )
+        partSaveStatus.Dispose()
+
+        print(f"[JOURNAL] Part saved: {prt_file}")
+
+        # Close all parts to ensure changes are written to disk and not cached in memory
+        # This is critical so the solve journal loads the updated PRT from disk
+        theSession.Parts.CloseAll(NXOpen.BasePart.CloseModified.UseResponses, None)
+        print(f"[JOURNAL] All parts closed to release file")
+
+    except Exception as e:
+        print(f"[ERROR] Failed to import expressions: {e}")
+        sys.exit(1)
+
+    print("[JOURNAL] Expression import complete!")
+
+
+if __name__ == '__main__':
+    main(sys.argv[1:])