fix(storybook-addon-vis): await the vitest module load before using the proxies

[unional]

Closes #835.

Problem

src/client/vitest_proxy.ts populated commands and page from a dynamic import that nothing awaited. Until it settled, browserContext was undefined and every property read through the commands proxy returned undefined — so the addon's beforeAll reading commands.setupVisSuite could fail with commands.setupVisSuite is not a function inside a run that genuinely is vitest browser mode. Ordering, not detection; the #829 guard is untouched.

Why the import stays dynamic

src/index.ts is the Storybook preview annotation entry, so this module is also evaluated in a plain Storybook preview where vitest and vitest/browser are not available. Hoisting to a static import (or a top-level await) would break that, so the fix enforces the ordering instead of removing the asynchrony.

Fix

• A command read before the import settles now returns a function that awaits the load and then delegates. Browser commands are async RPC calls, so this closes the window for every consumer of the proxy — including vis.setup() via storybook-addon-vis/vitest-setup — without each call site opting in.
• whenVitestProxyReady() exposes the load, and the addon's beforeAll awaits it before page and getCurrentTest (both read synchronously, so they cannot defer themselves).
• Outside a vitest browser run nothing is loaded and commands keeps yielding undefined, so the isRunningInTest check causes problems during agentic debugging #829 guards stay in charge.

Test

The timing is not observable on the module-level proxy (its import has long settled by the time a test runs), so createVitestProxy is exported and driven with loaders that stay pending until the test resolves them — the ordering is proven directly rather than raced.

Reverting only the proxy change turns 3 of the 7 new tests red (expected 'undefined' to be 'function'). Full package suite: 83 passed, plus pnpm build, tsc --noEmit, and biome check clean.

🤖 Generated with Claude Code

https://claude.ai/code/session_01NLB1dHgUEekHmMNj4G7R63

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🦋 Changeset detected

Latest commit: f450ead

The changes in this PR will be included in the next version bump.

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Name	Type
storybook-addon-vis	Patch

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