Fix timezone mismatch and OAuth profile field access

- Add getLatestDateWithData() helper that queries the most recent date
  with price data instead of using server UTC time
- Cache latest date for 5 minutes to reduce database queries
- Update all date-dependent endpoints to use database-relative dates
- Fix OAuth callback profile field access (use profile.email instead
  of profile.emails[0].value)
- Remove loginCount from $setOnInsert to avoid MongoDB conflict error

middleware/passport.js

@@ -11,9 +11,15 @@ const configurePassport = (passport, db) => {
   },
   async (accessToken, refreshToken, profile, done) => {
     try {
+      // Safely extract email
+      const email = profile.emails?.[0]?.value;
+      if (!email) {
+        return done(new Error('No email found in Google profile'), null);
+      }
+
       const userProfile = {
         googleId: profile.id,
-        email: profile.emails[0].value,
+        email: email,
         name: profile.displayName,
         picture: profile.photos?.[0]?.value || null
       };
@@ -21,6 +27,7 @@ const configurePassport = (passport, db) => {
       const user = await findOrCreateUser(db, userProfile);
       done(null, user);
     } catch (error) {
+      console.error('Passport strategy error:', error);
       done(error, null);
     }
   }));