perf(get-component): cache acceptLanguageParser.parse results

[ricardo-devis-agullo]

acceptLanguageParser.parse is called on every data-provider request with
the same Accept-Language header value. Since it's a pure function (same
input → same output), cache the result using the existing nice-cache instance
keyed by the raw header string.

This avoids repeated parsing of identical Accept-Language headers across
concurrent and sequential requests from the same browser.

[ricardo-devis-agullo]

Closing as superseded.

The original goal (avoid re-parsing the same Accept-Language header on every data-provider call) is already covered better on master by the lazy per-request getter introduced in the Jul 23 perf work (get acceptLanguage + parsedAcceptLanguage ??= in get-component.ts):

• parse only if the data provider actually reads context.acceptLanguage
• at most one parse per request

Cross-request caching of parsed headers (this PR’s approach via nice-cache) is a smaller incremental win and not worth rebasing/conflict-resolving on top of that. If we ever want process-wide caching later, it can be a fresh bounded-cache change on the getter — not this branch.