docs: add breakpoint debugging guide

[theetrain]

Closes #7781, relates to #1144

• Add breakpoint debugging documentation to the 'appendix' section

While testing with the Node.js inspector, I tried to enable server-side breakpoint debugging, but was not successful. The sourcemaps are being generated, but only client-side code connect to chrome devtools. VSCode breakpoint debugging works well.

I'm hoping there could be a way to debug server-side code within chrome devtools as well, which would help developers who aren't using VSCode, but I'm unsure whose domain this falls in: SvelteKit, Vite, or something else.

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[benmccann]

I think it'd be helpful to make this npm run dev to match the text above and real projects so that the user can copy/paste this example

[theetrain]

Thanks, Ben! I also added a link to Svelte Inspector for good measure.

[Conduitry]

Proposed changes to the svelte.dev site need to target the svelte-4 branch, not main.

[Conduitry]

Apologies, I can't read. This is kit.

[benmccann]

Suggested change

	"name": "Run npm start",
	"name": "Run npm dev",

[benmccann]

Can we change the page prefix from 15- to 25-? I'd like to keep the integrations page coming first

[benmccann]

Suggested change

	With the build-in debug terminal, you can set up breakpoints in source files within VSCode.
	With the built-in debug terminal, you can set up breakpoints in source files within VSCode.

[benmccann]

@theetrain I think there are a couple comments outstanding on this PR. If you're able to address them I'd love to get this in. We'll be restructuring the docs and closing any open PRs, so I'd like to get it in before that happens