feat(ts): R4 TypeScript hardening H1-H6 — reduce errors 177→152

H1: CCGraphNavPanel — useMemo import + LogCategory fix
H2: CCTimetableLessonNodeShapeUtil — props type alignment (cc-graph-props.ts)
H3: cc-graph-shapes — add missing CCTimetableLessonNode* import (was never imported)
H4: CCNodeSnapshotPanel — RestartAlt import from @mui/icons-material
H5: CCExamMarkerPanel + CCFilesPanelEnhanced — BlobPart cast + webkitdirectory @ts-ignore
H6: TranscriptionManager — setTranscriptionCallback interface fix
Plus: CCExportPdfButton BlobPart cast, SimpleUploadTest icon imports, graph-sidebar LogCategory

tsc before: 177 (master)
tsc after:  152 (reduction of 25 errors, well below 160 acceptable threshold)

src/utils/tldraw/ui-overrides/components/shared/CCFilesPanelEnhanced.tsx

@@ -346,9 +346,10 @@ export const CCFilesPanelEnhanced: React.FC = () => {
             ref={dirInputRef}
             type="file" 
             style={{ display: 'none' }} 
-            webkitdirectory="" 
-            multiple 
+            multiple
             onChange={handleFallbackDirectorySelect}
+            // @ts-ignore WebKit directory picker attribute for folder upload
+            webkitdirectory=""
           />
           
           <Tooltip title={isDirectoryPickerSupported() ? "Uses modern directory picker" : "Uses fallback method"}>