Spanish (es): Catch-up with EN version

Translate remaining messages and review fuzzy translations.
As of 6/5/24, current translation stats are:
```
es.po
3129 translated messages, 450 fuzzy translations, 194 untranslated messages.
```
### Steps:
1. Sync your branch with `main`.
2. Recreate `messages.pot`:
```shell
MDBOOK_OUTPUT='{"xgettext": {"pot-file": "messages.pot", "granularity": 0}}' \
mdbook build -d po
```
3. Merge with the `es.po`:
```shell
msgmerge --update po/es.po po/messages.pot
```
4. Edit the `es.po` file with your favorite PO editor.