chore(deps): update dependencies across the monorepo (#44)

* chore(deps): update dependencies across the monorepo

Bump all dependencies to their latest versions within current semver
ranges, plus a few low-risk major upgrades:

- zustand 4 -> 5 (store already uses the v5 curried API)
- @vitejs/plugin-react 4 -> 5 (peer-compatible with vite 7)
- vite-plugin-svgr 4 -> 5
- Remove deprecated @types/mixpanel-browser (mixpanel-browser ships
  its own types since 2.47)
- Format 10 files per prettier 3.9 union-type rules

Held back (risky majors for follow-up PRs): TypeScript 7, Vite 8,
Astro 7/Starlight 0.41, ESLint 10 ecosystem, MUI 9, zod 4, firebase 12,
Stripe SDK majors, AI SDK majors (openai 7, @google/genai 2, groq-sdk 1,
@anthropic-ai/sdk 0.117), babel-plugin-formatjs 13, cross-env 10,
dotenv 17. @tauri-apps/* pinned at 2.10.x to stay in lockstep with the
Rust crates (tauri =2.10.3 in Cargo.lock).

Verified: pnpm build (10/10), lint, check-types, desktop unit tests
(313 passed), utilities tests, and formatjs extraction output is
unchanged.

Co-authored-by: arena-agent <297053741+arena-agent@users.noreply.github.com>

* chore(deps): upgrade majors: MUI 9, zod 4, firebase 12, Astro 7, Stripe 6, pnpm 10.34

Co-authored-by: arena-agent <297053741+arena-agent@users.noreply.github.com>

* chore(deps): remove unused packages and dead Stripe config

Verified via depcheck + manual source audit that nothing imports these:

- @fontsource/roboto (only a quoted CSS family string remains)
- @stripe/react-stripe-js, @stripe/stripe-js (payment UI was removed)
- @tauri-apps/plugin-sql, @tauri-apps/plugin-updater (unused JS
  wrappers; the Rust crates are untouched)
- class-variance-authority
- ts-node (WebdriverIO runs TS specs natively)
- @azure/openai (azure-openai.utils.ts uses AzureOpenAI from the openai SDK)
- wavefile (WAV writing is hand-rolled in desktop's audio.utils.ts)
- zod-to-json-schema from @maus-inc/voice-ai (only desktop uses it)
- typescript at the repo root (every workspace pins its own)

Also removes the now-dead VITE_STRIPE_PUBLIC_KEY from the committed
.env files and its vite-env.d.ts declaration.

Co-authored-by: arena-agent <297053741+arena-agent@users.noreply.github.com>

* test(voice-ai): wire up the orphaned groq unit test

packages/voice-ai had a vitest spec in test/ that nothing could run:
no vitest devDependency and no test script. It is fully mocked and
needs no provider keys, so give the package a vitest setup like
packages/utilities and let turbo discover it.

Co-authored-by: arena-agent <297053741+arena-agent@users.noreply.github.com>

---------

Co-authored-by: Owie6789 <151057755+Owie6789@users.noreply.github.com>
Co-authored-by: arena-agent <297053741+arena-agent@users.noreply.github.com>