fix(ext-bridge): Throw error that indicates what might went wrong

[gandie]

What & why

Throw better error message as reminder when firing up extension frontend via ext-bridge. The timeout sent me off looking for network and timing issues, while i actually just forgot to initialize the bridge properly 😅

Checklist

• PR title is a Conventional Commit and matches the base branch above
• pnpm lint is clean and pnpm affected:test passes (browser tests if
  behavior changed)
• Generated code is committed (git diff is empty after the relevant
  build:* targets)
• User-facing strings added to both de-DE and en-US locale files
• Docs updated if a public API changed; intentional visual changes get
  updated snapshots / the update-screenshots label

[github-actions]

Coverage Report for ./packages/components/

Status	Category	Percentage	Covered / Total
🔵	Lines	75.25%	1180 / 1568
🔵	Statements	74.81%	1209 / 1616
🔵	Functions	69.94%	270 / 386
🔵	Branches	69.4%	617 / 889

File Coverage

No changed files found.

Generated in workflow #7025 for commit 910a59a by the Vitest Coverage Report Action

[github-actions]

🚀 Preview Deployment

Preview environments are ready:

Type	URL
docs	pr-3315.docs.review.flow-components.de
storybook	pr-3315.storybook.review.flow-components.de

Images:

• docs: ghcr.io/mittwald/flow/docs:pr-3315
• storybook: ghcr.io/mittwald/flow/storybook:pr-3315