chore(deps): drop the unused direct vite devDependency

[keonik]

Supersedes #323, which bumped this pin to ^8 instead of asking whether it should exist.

The pin was never used

Nothing in the repo imports vite. vitest.config.mts imports from vitest/config, and the only mention anywhere was line 130 of package.json. vitest declares vite in its own dependencies (not just peers):

deps.vite     = ^6.0.0 || ^7.0.0 || ^8.0.0
peerDeps.vite = ^6.0.0 || ^7.0.0 || ^8.0.0

so it installs and resolves vite with or without us.

What the pin actually cost

Holding ^6.0.0 while vitest wanted 7 meant the lockfile carried two of everything:

before                              after
"vite":        ["vite@6.4.3"]       "vite": ["vite@7.3.6"]
"vitest/vite": ["vite@7.3.6"]
esbuild@0.25.12 + esbuild@0.27.7    esbuild@0.27.7
  ...and @esbuild/* binaries for both platforms sets

Net -58 lines of bun.lock, one vite, one esbuild.

Verification

• bun run build — OK
• bun run test — 37/37 files, 70 passed, 1 skipped (unchanged from main)
• bun run lint, bun run format:check — clean

No changeset: devDependencies are not published (files: ["dist"]), so this ships nothing to users.