feat: add source name logging to $inspect.trace

[Ocean-OS]

This adds name logging to $inspect.trace. Currently, $inspect.trace logs the type of dependency ($state or $derived), its current value, and a few stack traces related to it. In this PR, to better understand your dependencies, it includes the name of each dependency— if it's a variable, it'll log its name, and if it's an object property, it'll log the path (eg object.foo.bar.baz[0]).

Probably closes #15954

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[changeset-bot]

🦋 Changeset detected

Latest commit: 4047913

The changes in this PR will be included in the next version bump.

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svelte	Minor

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[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@16060

[Rich-Harris]

What does PROXY_REMOVE_PATH do? No tests fail if I remove it altogether

[Rich-Harris]

I removed the tag_if_necessary stuff, because remnants of wrapper functions like that can end up in prod bundles (optimizers are rightly reluctant to remove unused arguments, because they affect fn.length), and because optimizers will occasionally do strange things with wrapper functions (terser/terser#1617)

[Rich-Harris]

It does the [$state proxy] tag when a proxy is shared by two sources

Is that desirable? In the very rare case that two sources share a single proxy, replacing foo.n with [$state proxy].n just makes it harder to see that either thing is being mutated. I think we'd be better off just leaving the path intact. The worst case scenario is that someone who doesn't realise that bar === foo is momentarily confused to see foo.n show up as having changed in response to a bar.n update, but [$state.proxy] doesn't make that any clearer — either way you would need to look at the UpdatedAtError trace to understand where the change originated.

If we get rid of PROXY_REMOVE_PATH we can simplify things a bit: #16126

[Rich-Harris]

This is a huge improvement! Makes $inspect.trace() so much more useful. Spotted some gibberish code in the existing trace implementation but was already getting carried away with the PR, so will address it in a follow-up.

Also, I broke the tests when I swapped the labels around — fixing