fix: increase # of emails fetched to find letters

Might help fix an issue that @martinsrna was facing where his Substack
newsletters weren't showing up in the "Letters" page. I'm guessing that
this was because there were no such Substack messages in his last 500
emails and thus the app couldn't detect them.

So, I've upped the # of messages fetched to 2500 (in batches of 100).

components/letters.tsx

@@ -163,7 +163,7 @@ export default function Letters() {
 
   useEffect(() => {
     if (!data) return;
-    void setSize((prev) => (prev >= 10 ? prev : prev + 1));
+    void setSize((prev) => (prev >= 25 ? prev : prev + 1));
   }, [data, setSize]);
   useEffect(() => {
     setSelected(new Set(user.filter.senders));

lib/api/get/letters.ts

@@ -11,7 +11,7 @@ export default async function getLetters(
   logger.verbose(`Fetching letters for ${user}...`);
   const client = gmail(user.token);
   const { data } = await client.users.messages.list({
-    maxResults: 50,
+    maxResults: 100,
     userId: 'me',
     pageToken,
   });

lib/api/update/gmail-messages.ts

@@ -7,6 +7,9 @@ import gmail from 'lib/api/gmail';
  * 1. Removes the label from messages that are not from our specified senders.
  * 2. Adds the label to messages that are from our specified senders and do not
  *    yet have the label.
+ * @todo Ensure that Gmail supports sending us 2500 messages (and doesn't have
+ * a cap at e.g. 500 letters per request). If it does have a cap, we should use
+ * the `nextPageToken` to fetch and update a total of 2500 messages.
  * @todo Implement the removal process using "Doesn't have" Gmail filters:
  * @example label:tutorbook -{from:team@tutorbook.org}
  */
@@ -15,7 +18,7 @@ export default async function updateGmailMessages(user: User): Promise<void> {
   const client = gmail(user.token);
   const { data } = await client.users.messages.list({
     q: `from:(${user.filter.senders.join(' OR ')})`,
-    maxResults: 1000,
+    maxResults: 2500,
     userId: 'me',
   });
   await client.users.messages.batchModify({