fix(plugin-vue): disable oxc jsx.refresh for Vue SFCs to prevent React Fast Refresh injection (fix #798)

[AmariahAK]

What is this PR solving?

When @vitejs/plugin-react is present in the same Vite config, it sets
config.oxc.jsx.refresh = true globally. The Vue plugin's TS transpilation
step in transformMain blindly spreads the full config.oxc into
transformWithOxc, causing Oxc to inject $RefreshSig$ / $RefreshReg$
into Vue SFCs with <script setup lang="ts"> that use use* composables
(e.g. useSlots(), useRoute(), useStore()). On Vue-only pages these
globals don't exist, causing ReferenceError: $RefreshSig$ is not defined.
The fix explicitly overrides jsx.refresh to false in the Oxc transform
options for Vue SFCs, while preserving all other oxc config inheritance
(e.g. target for decorators support per #430).

What alternatives have been explored?

• Not spreading config.oxc at all, cherry-picking specific options only:
  Would break the existing behavior of inheriting user-configured oxc options
  like target. Also fragile against future oxc option additions.
• Blanking jsx entirely (jsx: undefined):
  Too aggressive — users with .tsx Vue components may have legitimate JSX
  config they want to flow through.
• Chosen approach — override only jsx.refresh:
  Surgical. Preserves all other oxc config inheritance while blocking the
  single problematic option. Self-documenting: makes it obvious that React
  Fast Refresh has no place in Vue SFC transforms.

Are there any parts that require more attention from reviewers?

The fix is a four-line addition. The key consideration is whether there are
other Oxc options beyond jsx.refresh that @vitejs/plugin-react or similar
React tooling might set globally that could also leak into Vue SFCs. I believe
refresh is the only one with this characteristic — other JSX options like
jsxRuntime and importSource are React-specific and wouldn't produce
meaningful output for .vue files anyway.

Tests included

A new test playground playground/vue-refresh-bug/ with:

• vite.config.ts setting oxc.jsx.refresh = true (simulating
  @vitejs/plugin-react)
• RefreshBug.vue — <script setup lang="ts"> calling useSlots()
• Two assertions: component renders without errors, and no $RefreshSig$
  or $RefreshReg$ appear in browser logs/page errors
  Full test suite (pnpm test-serve + pnpm test-build): 13 files, 104 tests,
  zero regressions.