[Web] Avoid redundant OPFS lookup on cache hit

[guan404ming]

Why

fetchWithCache ran addToCache (which calls store.has()) then readFromCache, doing two OPFS lookups on a cache hit.

How

• Read the cache first and return on a hit, skipping store.has()
• Fall back to addToCache then read only on a miss

[gemini-code-assist]

Code Review

This pull request optimizes the ArtifactOPFSCache by attempting to read from the cache first before performing an OPFS lookup on a cache hit. It also refactors readFromCache to return undefined on a cache miss instead of throwing an error, delegating the error handling to the caller. I have no feedback to provide as there are no review comments.

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[guan404ming]

cc @akaashrp

[akaashrp]

Thanks for the ping. Been a bit busy, will try to take a look either today or tomorrow.

[akaashrp]

LGTM

[guan404ming]

Thanks!