Add a settings link to the footer with i18n options & pwa instructions

[abidlabs]

Adds a new Settings link in the footer:

Clicking on the Settings link opens up a page that allows toggling the theme, localization, and pwa installation instructions:

While I was at it, I also went through and filled in many of the missing entries in our i18n translation files (thanks Claude!) in 35f8706.

Closes: #655, Closes: #785

[gradio-pr-bot]

🪼 branch checks and previews

•	Name	Status	URL
	Spaces	ready!	Spaces preview
	Website	ready!	Website preview
	Storybook	ready!	Storybook preview
🦄	Changes	detected!	Details

---

Install Gradio from this PR

pip install https://gradio-pypi-previews.s3.amazonaws.com/576cbb8e2b61c40676af620f1f2f0b0fc7df8b37/gradio-5.9.1-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@576cbb8e2b61c40676af620f1f2f0b0fc7df8b37#subdirectory=client/python"

Install Gradio JS Client from this PR

npm install https://gradio-npm-previews.s3.amazonaws.com/576cbb8e2b61c40676af620f1f2f0b0fc7df8b37/gradio-client-1.8.0.tgz

Use Lite from this PR

<script type="module" src="https://gradio-lite-previews.s3.amazonaws.com/576cbb8e2b61c40676af620f1f2f0b0fc7df8b37/dist/lite.js""></script>

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
@gradio/client	minor
@gradio/core	minor
gradio	minor

• Maintainers can select this checkbox to manually select packages to update.

With the following changelog entry.

Add a settings link to the footer with i18n options & pwa instructions

Maintainers or the PR author can modify the PR title to modify this entry.

Something isn't right?

• Maintainers can change the version label to modify the version bump.
• If the bot has failed to detect any changes, or if this pull request needs to update multiple packages to different versions or requires a more comprehensive changelog entry, maintainers can update the changelog file directly.