Fix sub-session tab switching: reset step state on sessionId change

Step components (Deskew, Dewarp, Crop, Orientation) had local state
guards that prevented reloading when sessionId changed via sub-session
tab clicks. Added useEffect reset hooks that clear all local state
when sessionId changes, allowing the component to properly reload
the new session's data.

Also renamed "Box N" to "Seite N" in BoxSessionTabs per user feedback.

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

admin-lehrer/components/ocr-pipeline/BoxSessionTabs.tsx

@@ -59,7 +59,7 @@ export function BoxSessionTabs({ parentSessionId, subSessions, activeSessionId,
             title={sub.name}
           >
             <span className="mr-1">{icon}</span>
-            Box {sub.box_index + 1}
+            Seite {sub.box_index + 1}
           </button>
         )
       })}

admin-lehrer/components/ocr-pipeline/StepCrop.tsx

@@ -17,6 +17,13 @@ export function StepCrop({ sessionId, onNext }: StepCropProps) {
   const [error, setError] = useState<string | null>(null)
   const [hasRun, setHasRun] = useState(false)
 
+  // Reset state when sessionId changes (e.g. switching sub-sessions)
+  useEffect(() => {
+    setCropResult(null)
+    setHasRun(false)
+    setError(null)
+  }, [sessionId])
+
   // Auto-trigger crop on mount
   useEffect(() => {
     if (!sessionId || hasRun) return

admin-lehrer/components/ocr-pipeline/StepDeskew.tsx

@@ -22,6 +22,14 @@ export function StepDeskew({ sessionId, onNext }: StepDeskewProps) {
   const [error, setError] = useState<string | null>(null)
   const [hasAutoRun, setHasAutoRun] = useState(false)
 
+  // Reset state when sessionId changes (e.g. switching sub-sessions)
+  useEffect(() => {
+    setSession(null)
+    setDeskewResult(null)
+    setHasAutoRun(false)
+    setError(null)
+  }, [sessionId])
+
   // Load session and auto-trigger deskew
   useEffect(() => {
     if (!sessionId || session) return

admin-lehrer/components/ocr-pipeline/StepDewarp.tsx

@@ -20,6 +20,13 @@ export function StepDewarp({ sessionId, onNext }: StepDewarpProps) {
   const [showGrid, setShowGrid] = useState(true)
   const [error, setError] = useState<string | null>(null)
 
+  // Reset state when sessionId changes (e.g. switching sub-sessions)
+  useEffect(() => {
+    setDewarpResult(null)
+    setDeskewResult(null)
+    setError(null)
+  }, [sessionId])
+
   // Load session info to get deskew_result (for fine-tuning init values)
   useEffect(() => {
     if (!sessionId) return

admin-lehrer/components/ocr-pipeline/StepOrientation.tsx

@@ -30,6 +30,14 @@ export function StepOrientation({ sessionId: existingSessionId, onNext, onSubSes
   const [dragOver, setDragOver] = useState(false)
   const [sessionName, setSessionName] = useState('')
 
+  // Reset state when sessionId changes
+  useEffect(() => {
+    setSession(null)
+    setOrientationResult(null)
+    setPageSplitResult(null)
+    setError(null)
+  }, [existingSessionId])
+
   // Reload session data when navigating back
   useEffect(() => {
     if (!existingSessionId || session) return