fix(Flutter): Fix Flutter platform includes

[kahest]

DESCRIBE YOUR PR

After moving Flutter as a guide under Dart, we forgot to rename the platform include files from flutter.mdx to dart.flutter.mdx, therefore Dart snippets are shown instead of Flutter-specific snippets.

Compare e.g. the Usage page:

(currently shown: Dart content)

(expected/with this PR: Flutter content)

IS YOUR CHANGE URGENT?

Help us prioritize incoming PRs by letting us know when the change needs to go live.

• Urgent deadline (GA date, etc.): no GA date, but lots of snippets etc. are currently wrong, so rather sooner than later
• Other deadline:
• None: Not urgent, can wait up to 1 week+

SLA

• Teamwork makes the dream work, so please add a reviewer to your PRs.
• Please give the docs team up to 1 week to review your PR unless you've added an urgent due date to it.
  Thanks in advance for your help!

PRE-MERGE CHECKLIST

Make sure you've checked the following before merging your changes:

• Checked Vercel preview for correctness, including links
• PR was reviewed and approved by any necessary SMEs (subject matter experts)
• PR was reviewed and approved by a member of the Sentry docs team

EXTRA RESOURCES

• Sentry Docs contributor guide

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
sentry-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Mar 31, 2025 5:46pm

2 Skipped Deployments

Name	Status	Preview	Comments	Updated (UTC)
changelog	⬜️ Ignored (Inspect)	Visit Preview		Mar 31, 2025 5:46pm
develop-docs	⬜️ Ignored (Inspect)	Visit Preview		Mar 31, 2025 5:46pm

[codecov]

Bundle Report

Changes will increase total bundle size by 495 bytes (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
sentry-docs-server-cjs	10.61MB	501 bytes (0.0%) ⬆️
sentry-docs-client-array-push	9.44MB	-6 bytes (-0.0%) ⬇️

Affected Assets, Files, and Routes:

view changes for bundle: sentry-docs-client-array-push

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
static/chunks/pages/_app-*.js	-3 bytes	868.67kB	-0.0%
static/chunks/8931-*.js	-3 bytes	397.42kB	-0.0%
server/middleware-*.js	-5.55kB	1.0kB	-84.74%
server/middleware-*.js	5.55kB	6.55kB	555.3% ⚠️
static/FVs_yGkGNl83j6C3orQe3/_buildManifest.js (New)	578 bytes	578 bytes	100.0% 🚀
static/FVs_yGkGNl83j6C3orQe3/_ssgManifest.js (New)	77 bytes	77 bytes	100.0% 🚀
static/oWDKXWNl_DQrLrJUysx5W/_buildManifest.js (Deleted)	-578 bytes	0 bytes	-100.0% 🗑️
static/oWDKXWNl_DQrLrJUysx5W/_ssgManifest.js (Deleted)	-77 bytes	0 bytes	-100.0% 🗑️

view changes for bundle: sentry-docs-server-cjs

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
1729.js	-3 bytes	1.58MB	-0.0%
../instrumentation.js	-3 bytes	911.63kB	-0.0%
9523.js	-3 bytes	887.68kB	-0.0%
../app/[[...path]]/page.js.nft.json	170 bytes	383.53kB	0.04%
../app/platform-redirect/page.js.nft.json	170 bytes	383.45kB	0.04%
../app/sitemap.xml/route.js.nft.json	170 bytes	381.42kB	0.04%