fix: Capture latest draft ID after save to prevent race condition

When sending an email with attachments, saveDraft() would destroy+create
the draft (generating a new ID), but handleSend() was using the old ID
from React state which hadn't updated yet. This caused "notFound" errors.

Fixed by making saveDraft() return the draft ID and using it directly
in handleSend() instead of relying on async state updates.

components/email/email-composer.tsx

@@ -150,8 +150,8 @@ export function EmailComposer({
   };
 
   // Auto-save draft functionality
-  const saveDraft = async () => {
-    if (!client) return;
+  const saveDraft = async (): Promise<string | null> => {
+    if (!client) return null;
 
     const toAddresses = to.split(",").map(e => e.trim()).filter(Boolean);
     const ccAddresses = cc.split(",").map(e => e.trim()).filter(Boolean);
@@ -159,7 +159,7 @@ export function EmailComposer({
 
     // Only save if there's some content
     if (!toAddresses.length && !subject && !body) {
-      return;
+      return null;
     }
 
     // Prepare attachments for draft
@@ -177,7 +177,7 @@ export function EmailComposer({
 
     // Only save if data has changed
     if (currentData === lastSavedDataRef.current) {
-      return;
+      return draftId;
     }
 
     setSaveStatus('saving');
@@ -199,10 +199,13 @@ export function EmailComposer({
 
       // Reset status after 2 seconds
       setTimeout(() => setSaveStatus('idle'), 2000);
+
+      return savedDraftId;
     } catch (error) {
       console.error('Failed to save draft:', error);
       setSaveStatus('error');
       setTimeout(() => setSaveStatus('idle'), 3000);
+      return null;
     }
   };
 
@@ -237,10 +240,15 @@ export function EmailComposer({
     const bccAddresses = bcc.split(",").map(e => e.trim()).filter(Boolean);
 
     if (toAddresses.length > 0 && subject && body) {
-      // Wait for any pending auto-save to complete
+      // Wait for any pending auto-save to complete and get the latest draft ID
+      let finalDraftId = draftId;
       if (saveTimeoutRef.current) {
         clearTimeout(saveTimeoutRef.current);
-        await saveDraft();
+        // saveDraft returns the new draft ID after destroy+create
+        const savedId = await saveDraft();
+        if (savedId) {
+          finalDraftId = savedId;
+        }
       }
 
       onSend?.({
@@ -249,7 +257,7 @@ export function EmailComposer({
         bcc: bccAddresses,
         subject,
         body,
-        draftId: draftId || undefined,
+        draftId: finalDraftId || undefined,
       });
 
       // Reset form