post: remove whitespace of textnote content (trim right only)

Send button should be disabled if there are only white spaces or
newlines, trimming only right as white spaces at the beginning
could mean somethig i.e in markdown.

src/main.js

@@ -427,7 +427,8 @@ writeForm.addEventListener('submit', async (e) => {
   if (!pubkey || !privatekey) {
     return onSendError(new Error('no pubkey/privatekey'));
   }
-  if (!writeInput.value) {
+  const content = writeInput.value.trimRight();
+  if (!content) {
     return onSendError(new Error('message is empty'));
   }
   const replyTo = localStorage.getItem('reply_to');
@@ -435,7 +436,7 @@ writeForm.addEventListener('submit', async (e) => {
   const newEvent = {
     kind: 1,
     pubkey,
-    content: writeInput.value,
+    content,
     tags,
     created_at: Math.floor(Date.now() * 0.001),
   };
@@ -462,7 +463,7 @@ writeForm.addEventListener('submit', async (e) => {
 });
 
 writeInput.addEventListener('input', () => {
-  publish.disabled = !writeInput.value;
+  publish.disabled = !writeInput.value.trimRight();
   updateElemHeight(writeInput);
 });
 writeInput.addEventListener('blur', () => sendStatus.textContent = '');