Fix custom amount CO2 tons display in offset order components

When using custom monetary amount, the header and UI were showing 0.00 tons
instead of the calculated CO2 tons based on the monetary amount.

Changes:
- OffsetOrder.tsx: Use actualOffsetTons (calculated from monetaryAmount) in header instead of raw tons parameter
- MobileOffsetOrder.tsx: Use baseTons in form message and slider display to correctly show total when using custom amount
- Both components now properly calculate and display CO2 tons from monetary amounts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/components/MobileOffsetOrder.tsx

@@ -100,9 +100,9 @@ export function MobileOffsetOrder({ tons, monetaryAmount, onBack }: Props) {
   useEffect(() => {
     setFormData(prev => ({
       ...prev,
-      message: `I would like to offset ${formatTons(actualOffsetTons)} tons of CO2 (${offsetPercentage}% of ${formatTons(tons)} tons) from my yacht's emissions.`
+      message: `I would like to offset ${formatTons(actualOffsetTons)} tons of CO2 (${offsetPercentage}% of ${formatTons(baseTons)} tons) from my yacht's emissions.`
     }));
-  }, [offsetPercentage, actualOffsetTons, tons]);
+  }, [offsetPercentage, actualOffsetTons, baseTons]);
 
   // Save offset percentage and portfolio ID to localStorage
   useEffect(() => {
@@ -385,7 +385,7 @@ export function MobileOffsetOrder({ tons, monetaryAmount, onBack }: Props) {
                   </span>
                 </div>
                 <div className="text-sm text-blue-600 mt-1">
-                  {offsetPercentage}% of {formatTons(tons)} tons total emissions
+                  {offsetPercentage}% of {formatTons(baseTons)} tons total emissions
                 </div>
               </div>
             </div>

src/components/OffsetOrder.tsx

@@ -226,7 +226,7 @@ export function OffsetOrder({ tons, monetaryAmount, onBack, calculatorType }: Pr
           Offset Your Impact
         </h2>
         <p className="text-lg text-gray-600">
-          You're about to offset {formatTons(tons)} tons of CO₂
+          You're about to offset {formatTons(actualOffsetTons)} tons of CO₂
         </p>
       </motion.div>