Fix Svelte module script formatting

[ony3000]

Summary

• add a regression test for issue Error when formatting Svelte files with module script containing type declaration #145 covering Svelte module scripts with type declarations
• refine both module and instance Svelte script AST nodes so class wrapping keeps offsets valid
• keep prettier-plugin-svelte dev dependency unchanged after reverting the v4 upgrade commit

Tests

• pnpm exec vitest run tests/svelte/issue-145
• pnpm exec vitest run tests/svelte/script-tag tests/svelte/issue-119 tests/svelte/issue-76
• pnpm test

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