i18n(fr): add guides/integrations.mdx

[ArmandPhilippot]

Description (required)

• Creates the French translation of guides/integrations.mdx based on changes from New Ecosystem tab #13571 and Fix casing and heading levels in guides/integrations.mdx #13596
• Updates the links to /guides/integrations in other pages

This basically merges the old integration-guides/index.mdx and reference/publish-to-npm.mdx but while I was there:

• I've done some rewording
• I tried to make the headings consistent (e.g. "Créer..." then "Développement de..." vs "Créer..." then "Développer...", this looks better in the TOC I think)
• The table in "Catégories" was translating the UI strings used in https://astro.build/integrations/ filters... this can be confusing. So, I added the translation between parentheses. This is not ideal with small devices because of the table, but I don't think this looks too bad.

Related issues & labels (optional)

• Suggested label: i18n

[netlify]

✅ Deploy Preview for astro-docs-2 ready!

Built without sensitive environment variables

Name	Link
🔨 Latest commit	1a57e45
🔍 Latest deploy log	https://app.netlify.com/projects/astro-docs-2/deploys/69ca513336e3b300081593b8
😎 Deploy Preview	https://deploy-preview-13598--astro-docs-2.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[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
fr/guides/integrations.mdx	Localization added, will be marked as complete.
fr/guides/on-demand-rendering.mdx	Localization changed, will be marked as complete.
fr/guides/upgrade-to/v3.mdx	Localization changed, will be marked as complete.
fr/guides/upgrade-to/v4.mdx	Localization changed, will be marked as complete.
fr/guides/upgrade-to/v5.mdx	Localization changed, will be marked as complete.
fr/reference/cli-reference.mdx	Localization changed, will be marked as complete.
fr/reference/content-loader-reference.mdx	Localization changed, will be marked as complete.
fr/reference/errors/client-address-not-available.mdx	Localization changed, will be marked as complete.
fr/reference/errors/no-matching-renderer.mdx	Localization changed, will be marked as complete.
fr/reference/modules/astro-app.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.