chore: Project cleanup and Canvas UX improvements (Phase 7-9)

## Cleanup (v0.5.0)
- Delete 102+ orphaned MCP session temp files
- Remove build artifacts (htmlcov, dist, __pycache__)
- Archive superseded plan docs (RALPH_LOOP V2/V3, CANVAS V3, etc.)
- Move debug/analysis scripts from tests/ to tools/analysis/
- Archive redundant NX journals to archive/nx_journals/
- Archive monolithic PROTOCOL.md to docs/archive/
- Update .gitignore with missing patterns
- Clean old study files (optimization_log_old.txt, run_optimization_old.py)

## Canvas UX (Phases 7-9)
- Phase 7: Resizable panels with localStorage persistence
  - Left sidebar: 200-400px, Right panel: 280-600px
  - New useResizablePanel hook and ResizeHandle component
- Phase 8: Enable all palette items
  - All 8 node types now draggable
  - Singleton logic for model/solver/algorithm/surrogate
- Phase 9: Solver configuration
  - Add SolverEngine type (nxnastran, mscnastran, python, etc.)
  - Add NastranSolutionType (SOL101-SOL200)
  - Engine/solution dropdowns in config panel
  - Python script path support

## Documentation
- Update CHANGELOG.md with recent versions
- Update docs/00_INDEX.md
- Create examples/README.md
- Add docs/plans/CANVAS_UX_IMPROVEMENTS.md

atomizer-dashboard/frontend/src/components/canvas/panels/NodeConfigPanelV2.tsx

@@ -315,18 +315,106 @@ function ModelNodeConfig({ spec }: SpecConfigProps) {
 }
 
 function SolverNodeConfig({ spec }: SpecConfigProps) {
+  const { patchSpec } = useSpecStore();
+  const [isUpdating, setIsUpdating] = useState(false);
+  
+  const engine = spec.model.sim?.engine || 'nxnastran';
+  const solutionType = spec.model.sim?.solution_type || 'SOL101';
+  const scriptPath = spec.model.sim?.script_path || '';
+  const isPython = engine === 'python';
+  
+  const handleEngineChange = async (newEngine: string) => {
+    setIsUpdating(true);
+    try {
+      await patchSpec('model.sim.engine', newEngine);
+    } catch (err) {
+      console.error('Failed to update engine:', err);
+    } finally {
+      setIsUpdating(false);
+    }
+  };
+  
+  const handleSolutionTypeChange = async (newType: string) => {
+    setIsUpdating(true);
+    try {
+      await patchSpec('model.sim.solution_type', newType);
+    } catch (err) {
+      console.error('Failed to update solution type:', err);
+    } finally {
+      setIsUpdating(false);
+    }
+  };
+  
+  const handleScriptPathChange = async (newPath: string) => {
+    setIsUpdating(true);
+    try {
+      await patchSpec('model.sim.script_path', newPath);
+    } catch (err) {
+      console.error('Failed to update script path:', err);
+    } finally {
+      setIsUpdating(false);
+    }
+  };
+
   return (
-    <div>
-      <label className={labelClass}>Solution Type</label>
-      <input
-        type="text"
-        value={spec.model.sim?.solution_type || 'Not configured'}
-        readOnly
-        className={`${inputClass} bg-dark-900 cursor-not-allowed`}
-        title="Solver type is determined by the model file."
-      />
-      <p className="text-xs text-dark-500 mt-1">Detected from model file.</p>
-    </div>
+    <>
+      {isUpdating && (
+        <div className="text-xs text-primary-400 animate-pulse">Updating...</div>
+      )}
+      
+      <div>
+        <label className={labelClass}>Solver Engine</label>
+        <select
+          value={engine}
+          onChange={(e) => handleEngineChange(e.target.value)}
+          className={selectClass}
+        >
+          <option value="nxnastran">NX Nastran (built-in)</option>
+          <option value="mscnastran">MSC Nastran (external)</option>
+          <option value="python">Python Script</option>
+          <option value="abaqus" disabled>Abaqus (coming soon)</option>
+          <option value="ansys" disabled>ANSYS (coming soon)</option>
+        </select>
+        <p className="text-xs text-dark-500 mt-1">
+          {isPython ? 'Run custom Python analysis script' : 'Select FEA solver software'}
+        </p>
+      </div>
+      
+      {!isPython && (
+        <div>
+          <label className={labelClass}>Solution Type</label>
+          <select
+            value={solutionType}
+            onChange={(e) => handleSolutionTypeChange(e.target.value)}
+            className={selectClass}
+          >
+            <option value="SOL101">SOL101 - Linear Statics</option>
+            <option value="SOL103">SOL103 - Normal Modes</option>
+            <option value="SOL105">SOL105 - Buckling</option>
+            <option value="SOL106">SOL106 - Nonlinear Statics</option>
+            <option value="SOL111">SOL111 - Modal Frequency Response</option>
+            <option value="SOL112">SOL112 - Modal Transient Response</option>
+            <option value="SOL200">SOL200 - Design Optimization</option>
+          </select>
+        </div>
+      )}
+      
+      {isPython && (
+        <div>
+          <label className={labelClass}>Script Path</label>
+          <input
+            type="text"
+            value={scriptPath}
+            onChange={(e) => handleScriptPathChange(e.target.value)}
+            placeholder="path/to/solver_script.py"
+            className={`${inputClass} font-mono text-sm`}
+          />
+          <p className="text-xs text-dark-500 mt-1">
+            Python script must define solve(params) function
+          </p>
+        </div>
+      )}
+    </>
   );
 }