fix(test): wrap async provider/hook updates in act() to clear CI log noise

[grimen]

What

Fixes #3814 — act(...) warnings flooding Concourse/CI logs across many test suites.

Many synchronous render-and-assert tests render providers/hooks whose async useEffect work (KeyStore reads, SDK init, Apollo queries, animations) resolves after the synchronous test body returns — outside act() — emitting:

An update to <Component> inside a test was not wrapped in act(...).

These are benign (tests pass) but produced 252 console.error warnings codebase-wide, burying real failures in CI output.

How

• Add shared helper __tests__/helpers/flush-effects.ts → flushEffects(), which settles pending promises/microtasks inside act() via a setImmediate drain. This is deeper than a bare await act(async () => {}) — several suites already had that and still warned through.
• Apply it across 28 suites to await the async settle in the affected synchronous tests.
• For real-timer animations (StepsProgressBar ~120ms, react-native-modal ~300–400ms) and fake-timer suites where setImmediate flushing doesn't apply, use the idiomatic act()-wrapped timer advance instead.

This resolves the warnings by properly awaiting async initialization — it does not suppress them. No console.error mocking, no production code changes, no weakened assertions.

Verification

Check	Result
act(...) warnings (full suite)	252 → 0
Full test suite	no new failures
tsc -p .	✅ pass
eslint (changed files)	✅ pass

Out of scope (pre-existing)

__tests__/components/blink-card/blink-card.spec.tsx › displays valid thru date fails on a date-sensitive assertion (12/ 28 vs 11/ 28) on the untouched baseline too — a separate, pre-existing issue not addressed here.

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