Cache Revalidation

[mookums]

This adds Cache Revalidation, properly checking no-cache and stale entries.

[karlseguin]

I tested it and it doesn't work. Wrong results + crash.

[krichprollsch]

@mookums Do you have a corresponding PR on demo to add more tests? found lightpanda-io/demo#185

[krichprollsch]

I think we should apply immediately https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/Caching#heuristic_caching

But it may be challenging to parse the Last-Modified header. Maybe we could go simpler, w/ a short max-age (10min?) + consider the cache control is no-cache and only if the response contains either a Last-Modifed or an etag.

[mookums]

Duration regression is from the cache tests being added to puppeteer. Any objections to just upping the average time in the CI test?

[krichprollsch]

Duration is about puppeteer/cdp.js test only. Your change shouldn't have an impact on it, cache is not enable 🤔

[krichprollsch]

Here is another comment from Claude about DeferredLayer (lines are outdated)
Not sure if it's correct r not 🤔

• DeferringLayer doesn't propagate .handled — its deferred-replay paths (DeferringLayer.zig:283- and :333-) only branch on .abort vs not, treating .handled like .proceed. If a CacheLayer 304 (.handled) ever sits inside a DeferringLayer, the replay would forward header and continue replaying data/done, double-forwarding. Likely not a current combination, but the asymmetry is a latent trap.

[krichprollsch]

I think we are good to merge. Anything to change from your POV @karlseguin?

[karlseguin]

@krichprollsch LGTM