fix: strip import attributes from dynamic imports in dev mode

[teee32]

Description

Dynamic imports with import attributes (e.g. import('./data.json', { with: { type: 'json' } })) cause runtime errors in dev mode:

• Firefox: SyntaxError: missing ) after argument list — Firefox does not yet support import attributes syntax
• Chrome: Failed to load module script: Expected a JSON module script but the server responded with a MIME type of "text/javascript"

Vite already strips import attributes from static imports during dev (since it processes typed imports internally), but dynamic imports were explicitly excluded by the !isDynamicImport guard at importAnalysis.ts:523. This PR extends the attribute stripping to also cover dynamic imports, adjusting the removal range for the parenthesized syntax.

Fixes #19095

Alternatives considered

• Serving JSON files with application/json MIME type when import attributes are present — this would fix Chrome but not Firefox, and would conflict with Vite's JSON-to-JS transform pipeline.
• Handling this in the build pipeline — not needed since Rolldown/Rollup already handles import attributes during build. The issue is dev-only.

Reviewer notes

The core change is small (one condition change + one new branch in importAnalysis.ts). The key insight is that for dynamic imports, import attributes are the second argument inside import(specifier, options), so the removal range is [end, expEnd - 1) (after specifier, before closing paren), vs [end + 1, expEnd) for static imports.

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• Read the Contributing Guidelines
• Checked that there isn't already a PR that solves the problem the same way
• No documentation update needed (dev server internal behavior)
• Included a regression test (dynamic import with import attributes in JSON playground, serve-only)