feat: Promote Persona Note as default

[enzi221]

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Summary

Removes the Persona Note option, and localizes its placeholder.

Related Issues

None.

Changes

The Note has been around for a while, yet quite a few users still don't know it exists, and some even said that they had considered developing dedicated plugins for it. It is too minor and stable to be experimental, and too essential to sit behind an option, so this PR removes the option and always enables the persona note.

This PR localizes the Note's placeholder as well.

Changes are split into two commits. If you would rather keep the option, I can drop the second one. Then, this PR will be a bug fix and a localization:

• Moves the "Note" label inside the conditional block, so it no longer appears without its input when the option is off. As-is:
  
• Localization key for the placeholder.
• (Still removes experimental status)

Impact

All users can see the persona note's text input.

[cubicj]

I went through 30b41e6 on this. The note was already saved, shown next to the persona name in the persona list, and carried through PNG export whether or not the option was on. The option only hid the edit field, so removing it opens that field for everyone, and the label no longer shows up without its input. Personas with no saved note, such as ones imported from older PNGs, come up with an empty field and save like any other note once filled in. pnpm check, pnpm test, and pnpm build are clean on this head.

Personally, I think the note is useful enough to be on by default.

Approving — thanks for the contribution!