chore(deps-dev): bump the jest family to 30.5.1 together + group it for dependabot

[genwave-radio]

🐛 What

Supersedes #682 (@jest/globals alone, red) and #683 (jest-environment-jsdom alone, green by luck). Dependabot should auto-close both once this merges.

🔍 Why #682 fails

Every jest package pins its siblings to the exact same version. @jest/globals 30.5.1 demands @jest/expect 30.5.1, while the still-30.4.2 jest keeps @jest/expect 30.4.1 hoisted, so npm nests a second copy under @jest/globals (plus 35 other nested duplicates in that lockfile).

The specs import @testing-library/jest-dom/jest-globals, which augments Matchers on the top-level copy. expect from @jest/globals comes from the nested copy and never sees the augmentation:

error TS2339: Property 'toBeInTheDocument' does not exist on type 'Matchers<void, HTMLElement> ...'

Reproduced on the #682 branch: 1,455 errors in typecheck:specs. Same rule that bit the 29→30 move in July.

✅ Fix

1. npm install -D jest@30.5.1 @jest/globals@30.5.1 jest-environment-jsdom@30.5.1 jest-environment-node@30.5.1 in one go. The lockfile ends with a single @jest/expect and no nested @jest/globals.
2. .github/dependabot.yml: a groups entry for the jest family (jest, @jest/*, jest-environment-*) so future trains arrive as one PR. ts-jest stays out on its own 29.x cadence.

🧪 Verified locally

Step	Result
typecheck:specs	0 errors
tsc --noEmit	clean
jest	1,261 passed, 123 suites
lint	0 errors (20 pre-existing warnings)
next build	OK