fix: remove unused client nodes if CSR is disabled

[teemingc]

closes #9703

Seeing if we can remove client nodes if they're unused. Disabling CSR in combination with server-side resolution should help obscure routes.

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[Rich-Harris]

I don't think this is right. csr = false means that we don't load the client if we land on the page directly. If we navigate to the page from a different page with csr = true, then we can't 'unload' the client, we just treat it as a normal client-side navigation. With this change, that's impossible, because the client will attempt to import a non-existent module.

And it's not like we can opt out of client-side navigation in those cases, because we would need to either a) store the information about which pages have csr = false in the route manifest or b) fall back to a hard reload after a soft navigation failed. Neither seems desirable.

So I think the only time we would want to get rid of these files is if we know that all routes are csr = false, and in that case we'd just skip the client build altogether.

[teemingc]

I don't think this is right. csr = false means that we don't load the client if we land on the page directly. If we navigate to the page from a different page with csr = true, then we can't 'unload' the client, we just treat it as a normal client-side navigation. With this change, that's impossible, because the client will attempt to import a non-existent module.

Ah yeah, I overlooked that.

So I think the only time we would want to get rid of these files is if we know that all routes are csr = false, and in that case we'd just skip the client build altogether.

Skipping the client build might be a little tricky. We still use the CSS files generated from that build, which is also why we couldn’t simply omit the nodes from the client build but had to delete them after the build.

[Rich-Harris]

Ah. We don't generate CSS files during the server build?

[teemingc]

We do but our current logic parses the client manifest to associate the client stylesheets with the route. Let me see if I can rework that to use the server stylesheets instead...