i18n(ja): add guide routing

[Yusaku01]

Description

This PR is based on the following file:

https://github.com/withastro/docs/blob/main/src/content/docs/en/guides/routing.mdx

I'd appreciate it if you could review this when you have time 🫡

[astrobot-houston]

Lunaria Status Overview

🌕 This pull request will trigger status changes.

Learn more

By default, every PR changing files present in the Lunaria configuration's files property will be considered and trigger status changes accordingly.

You can change this by adding one of the keywords present in the ignoreKeywords property in your Lunaria configuration file in the PR's title (ignoring all files) or by including a tracker directive in the merged commit's description.

Tracked Files

File	Note
ja/basics/astro-pages.mdx	Localization changed, will be marked as complete.
ja/basics/layouts.mdx	Localization changed, will be marked as complete.
ja/guides/data-fetching.mdx	Localization changed, will be marked as complete.
ja/guides/endpoints.mdx	Localization changed, will be marked as complete.
ja/guides/middleware.mdx	Localization changed, will be marked as complete.
ja/guides/migrate-to-astro/from-create-react-app.mdx	Localization changed, will be marked as complete.
ja/guides/routing.mdx	Localization added, will be marked as complete.
ja/guides/upgrade-to/v6.mdx	Localization changed, will be marked as complete.
ja/guides/upgrade-to/v7.mdx	Localization changed, will be marked as complete.
ja/reference/errors/get-static-paths-invalid-route-param.mdx	Localization changed, will be marked as complete.
ja/reference/errors/get-static-paths-required.mdx	Localization changed, will be marked as complete.
ja/reference/errors/no-matching-static-path-found.mdx	Localization changed, will be marked as complete.
ja/tutorial/5-astro-api/2.mdx	Localization changed, will be marked as complete.
ja/tutorial/5-astro-api/3.mdx	Localization changed, will be marked as complete.
ja/tutorial/6-islands/4.mdx	Localization changed, will be marked as complete.

Warnings reference

Icon	Description
🔄️	The source for this localization has been updated since the creation of this pull request, make sure all changes in the source have been applied.

[github-actions]

Preview deployment

✅ Deployment complete!

• Latest commit: bab1946
• Preview: https://i18n-ja-routing.previews.docs.astro.build
• Workflow run: View logs