fix(kit): cast nuxt addVitePlugin calls past duplicate vite peer types

[antfubot]

Description

CI's Typecheck step is red on main: after the vite 8.3.1 bump, pnpm resolves vite's optional @vitejs/devtools peer to a different published version for each Nuxt-hosted devtools app's own dependency chain versus the one @nuxt/kit's addVitePlugin is typed against. Both installs are the same vite@8.3.1, but TypeScript treats them as structurally distinct because DevEnvironment's hotUpdate hook now flows through a private _pluginContextMap field, so vue-tsc rejects our own plugin objects as foreign Plugin instances in packages/oxc, packages/rolldown, and packages/vite's modules/rpc.ts.

Pinning the lockfile to a single @vitejs/devtools peer flavor (via overrides, peerDependencyRules.allowedVersions, and ignoreMissing) didn't hold — each Nuxt app instance re-resolves its own @nuxt/vite-builder → vite → @vitejs/devtools chain independently, so a lockfile-level fix would mean pinning every such chain across the monorepo. Instead, this adds a small addDevToolsVitePlugin helper at each addVitePlugin call site that casts past the structural mismatch, since the plugin objects are valid at runtime regardless of which peer flavor typed them.

Linked Issues

Additional context

Verified pnpm lint && pnpm test && pnpm typecheck && pnpm build all pass locally with this change (typecheck was the only broken step).

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@vitejs/devtools

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@vitejs/devtools-kit

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@vitejs/devtools-oxc

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@vitejs/devtools-rolldown

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@vitejs/devtools-vite

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@vitejs/devtools-vitest

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commit: ec3e160