fix(frontend): post-review fixes sprint 2

- MitreTechniquePicker: guard sync effect while dropdown open to prevent
  mid-stroke wipe when onChange(null,null) propagates back as null props
- SimulationList: replace window.location.href with navigate() to keep
  TanStack Query cache intact on row click
- SimulationFormPage: simplify redundant ternary on SOC form onSubmit
- SimulationFormPage: remove dead .replace(' ','T') on executed_at
  (backend already returns ISO 8601 with T separator)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/SimulationFormPage.tsx

@@ -86,7 +86,7 @@ export function SimulationFormPage(): JSX.Element {
         description: s.description ?? '',
         commands: s.commands ?? '',
         prerequisites: s.prerequisites ?? '',
-        executed_at: s.executed_at ? s.executed_at.replace(' ', 'T').slice(0, 16) : '',
+        executed_at: s.executed_at ? s.executed_at.slice(0, 16) : '',
         execution_result: s.execution_result ?? '',
       });
       setSoc({
@@ -117,6 +117,7 @@ export function SimulationFormPage(): JSX.Element {
   const socCanEdit = isSoc && (status === 'review_required' || status === 'done');
   const socBlocked = isSoc && (status === 'pending' || status === 'in_progress');
 
+  const canSaveSoc = socCanEdit || canEditEngagements;
   const rtDisabled = !canEditRT;
   const socDisabled = !canEditEngagements && !socCanEdit;
 
@@ -395,7 +396,7 @@ export function SimulationFormPage(): JSX.Element {
       {/* SOC card */}
       <form
         id="soc-form"
-        onSubmit={socCanEdit ? onSaveSOC : canEditEngagements ? onSaveSOC : (e) => e.preventDefault()}
+        onSubmit={canSaveSoc ? onSaveSOC : (e) => e.preventDefault()}
         noValidate
         className="card-product flex flex-col gap-md"
       >
@@ -441,7 +442,7 @@ export function SimulationFormPage(): JSX.Element {
           />
         </FormField>
 
-        {(socCanEdit || canEditEngagements) && (
+        {canSaveSoc && (
           <div className="flex items-center gap-md pt-sm border-t border-hairline">
             <button type="submit" form="soc-form" className="btn-primary" disabled={submitting}>
               {updateMutation.isPending ? 'Saving…' : 'Save SOC'}