fix(app): load component-test modules at the URLs Vite imports them by - #53091

Why

e2e (linux) fails on every PR against v2 (for example run 37175224254 on #53012) because two app component tests fail on every attempt:

• component-tests/browser-pane-restore.spec.ts:43 keeps a restored browser tab selected and undrawn until the desktop's first inventory
• component-tests/browser-pane-restore.spec.ts:65 keeps the browser tabs while the pane's Ipc is away and registers them again when it returns

Error: page.evaluate: Error: Language context must be used within a context provider
    at createHost (.../packages/app/src/runtime/extension/host.tsx)

Root cause

The component specs build Vite module URLs as `/@fs/${fileURLToPath(...)}`. On POSIX, fileURLToPath returns a path that starts with /, so the specs import /@fs//home/.../language.tsx (double slash). Vite rewrites host.tsx's own @/runtime/i18n/language import to /@fs/home/.../language.tsx (single slash). The browser treats these as two different modules, so the LanguageProvider the spec passes to the fixture provides one LanguageContext, while ExtensionHostProvider reads a different one.

The bug was already in the specs. #52868 (0048c97c27) exposed it by adding the Run app component tests step to CI. Windows passes because its paths become /@fs/C:/..., which is the same URL Vite uses.

What changes

• Add sourceURL(url) to packages/storybook/playwright/story.ts. It returns /@fs${url.pathname}, which matches the URLs Vite rewrites imports to on POSIX and Windows.
• Use it in every app and session-ui component spec that imported modules by /@fs URL. The other specs only load a single fixture each, so they weren't failing, but they had the same double-slash URLs.
• Regenerate the tracked story.d.ts.

No assertions change.

Verification

• Before the fix, on origin/v2 (macOS, which also produces /@fs//Users/...): bun run test:components -- browser-pane-restore.spec.ts --retries=0 fails both tests with the same Language context error.
• After the fix, from packages/app:
  • bun run test:components -- browser-pane-restore.spec.ts --retries=0: 2 passed
  • CI=1 bun run test:components: 92 passed, 0 flaky
• From packages/session-ui: CI=1 bun run test:components: 130 passed
• bun typecheck passes in packages/app and packages/session-ui.
• bun run check from the repo root: 36/36 tasks passed.