feat(client): Add a global refresh() to the Rust client

[sentry-junior]

#156 added manual refresh and with_refresh_threshold(None). In Rust, though, refresh() only exists as an Options method. The global store that init() and Options::builder()...init() create is a private OnceLock, so callers can't reach it. A Rust service that runs .with_refresh_threshold(None).init() therefore never reloads its values for the life of the process, while options() and features() keep serving the first snapshot.

Python doesn't have this gap. sentry_options.refresh() already refreshes the Python global. objectstore isn't affected either: it calls .build() and refreshes its own instance (getsentry/objectstore#549).

This PR adds sentry_options::refresh() -> Result<bool>, which refreshes the global store. It mirrors the Python function and returns NotInitialized when called before init(). The new test is in its own integration test binary, because it sets the process-wide store. Without the fix, that test does not compile.

The docs in setup.md and architecture.md now name sentry_options::refresh() for the global store. They overlap with the docs refresh in #201, which currently says the global store has no refresh(). Whichever PR merges second will need a small rebase.

Open question for review: should the Rust init() docs or the builder docs warn that with_refresh_threshold(None) needs a refresh driver? Today only the prose docs say so.

via @joshuarli.

--

View Junior Session [Sentry]