refactor(devtools): Mark interfaces as @sealed and @system as appropriate

[Josmithr]

APIs that were never intended for direct consumer use have been marked as @system.
These are:

• HasContainerKey

And APIs that were not intended to be extended by consumers have been marked as @sealed.
These are:

• ContainerDevtoolsProps
• DevtoolsProps
• HasContainerKey
• IDevtools

Additionally, interface properties have been marked as readonly.

Note that all of the affected APIs are @beta, so this change is not in violation of our breaking changes policy.
And in practice, it is unlikely to affect any users of our APIs.

Copilot reviewed 5 out of 7 changed files in this pull request and generated no suggestions.

Files not reviewed (2)

• packages/tools/devtools/devtools-core/api-report/devtools-core.alpha.api.md: Evaluated as low risk
• packages/tools/devtools/devtools-core/api-report/devtools-core.beta.api.md: Evaluated as low risk

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[msfluid-bot]

Code Coverage Summary

No packages impacted by the change.

---

Baseline commit: 645a1a0
Baseline build: 309185
Happy Coding!!

Code coverage comparison check passed!!

[msfluid-bot]

⯅ @fluid-example/bundle-size-tests: +245 Bytes

Metric Name	Baseline Size	Compare Size	Size Diff
aqueduct.js	467.24 KB	467.27 KB	⯅ +35 Bytes
azureClient.js	564.01 KB	564.06 KB	⯅ +49 Bytes
connectionState.js	724 Bytes	724 Bytes	■ No change
containerRuntime.js	263.43 KB	263.45 KB	⯅ +14 Bytes
fluidFramework.js	428.84 KB	428.85 KB	⯅ +14 Bytes
loader.js	134.18 KB	134.19 KB	⯅ +14 Bytes
map.js	42.71 KB	42.71 KB	⯅ +7 Bytes
matrix.js	150.15 KB	150.16 KB	⯅ +7 Bytes
odspClient.js	529.85 KB	529.89 KB	⯅ +49 Bytes
odspDriver.js	97.88 KB	97.9 KB	⯅ +21 Bytes
odspPrefetchSnapshot.js	42.81 KB	42.83 KB	⯅ +14 Bytes
sharedString.js	166.23 KB	166.24 KB	⯅ +7 Bytes
sharedTree.js	419.3 KB	419.3 KB	⯅ +7 Bytes
Total Size	3.38 MB	3.38 MB	⯅ +245 Bytes

---

Baseline commit: 645a1a0

Generated by 🚫 dangerJS against b73af22

[jzaffiro]

Docs look good pending one minor comment!

[github-actions]

🔗 No broken links found! ✅

Your attention to detail is admirable.

linkcheck output

> [email protected] ci:check-links /home/runner/work/FluidFramework/FluidFramework/docs
> start-server-and-test "npm run serve -- --no-open" 3000 check-links

1: starting server using command "npm run serve -- --no-open"
and when url "[ 'http://127.0.0.1:3000' ]" is responding with HTTP status code 200
running tests using command "npm run check-links"


> [email protected] serve
> docusaurus serve --no-open

[SUCCESS] Serving "build" directory at: http://localhost:3000/

> [email protected] check-links
> linkcheck http://localhost:3000 --skip-file skipped-urls.txt

Crawling...

Stats:
  170005 links
    1595 destination URLs
    1825 URLs ignored
       0 warnings
       0 errors