feat: remove recent conversions functionality from units

- Delete ConversionHistory component
- Remove history-related logic and state from MainConverter
- Clean up history imports and types in CommandPalette and storage utilities
- Remove history storage functions from lib/units/storage.ts

components/units/converter/MainConverter.tsx

@@ -6,7 +6,6 @@ import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/Card';
 import { Input } from '@/components/ui/Input';
 import { Button } from '@/components/ui/Button';
 import SearchUnits from './SearchUnits';
-import ConversionHistory from './ConversionHistory';
 import VisualComparison from './VisualComparison';
 import CommandPalette from '@/components/units/ui/CommandPalette';
 import {
@@ -21,7 +20,7 @@ import {
   type ConversionResult,
 } from '@/lib/units/units';
 import { parseNumberInput, formatNumber, cn } from '@/lib/utils';
-import { saveToHistory, getFavorites, toggleFavorite } from '@/lib/units/storage';
+import { getFavorites, toggleFavorite } from '@/lib/units/storage';
 
 export default function MainConverter() {
   const [selectedMeasure, setSelectedMeasure] = useState<Measure>('length');
@@ -93,39 +92,12 @@ export default function MainConverter() {
     setFavorites(getFavorites());
   }, []);
 
-  // Save to history when conversion happens (but not during dragging)
-  useEffect(() => {
-    if (isDragging) return; // Don't save to history while dragging
-
-    const numValue = parseNumberInput(inputValue);
-    if (numValue !== null && selectedUnit && conversions.length > 0) {
-      // Save first conversion to history
-      const firstConversion = conversions.find(c => c.unit !== selectedUnit);
-      if (firstConversion) {
-        saveToHistory({
-          from: { value: numValue, unit: selectedUnit },
-          to: { value: firstConversion.value, unit: firstConversion.unit },
-          measure: selectedMeasure,
-        });
-        // Dispatch custom event for same-window updates
-        window.dispatchEvent(new Event('historyUpdated'));
-      }
-    }
-  }, [inputValue, selectedUnit, conversions, selectedMeasure, isDragging]);
-
   // Handle search selection
   const handleSearchSelect = useCallback((unit: string, measure: Measure) => {
     setSelectedMeasure(measure);
     setSelectedUnit(unit);
   }, []);
 
-  // Handle history selection
-  const handleHistorySelect = useCallback((record: any) => {
-    setInputValue(record.from.value.toString());
-    setSelectedMeasure(record.measure);
-    setSelectedUnit(record.from.unit);
-  }, []);
-
   // Handle value change from draggable bars
   const handleValueChange = useCallback((value: number, unit: string, dragging: boolean) => {
     setIsDragging(dragging);
@@ -337,9 +309,6 @@ export default function MainConverter() {
           )}
         </CardContent>
       </Card>
-
-      {/* Conversion History */}
-      <ConversionHistory onSelectConversion={handleHistorySelect} />
     </div>
   );
 }