fix: preserve uni-app root style shell during hmr

[sonofmagic]

Summary

• preserve framework-owned pure local import root style wrappers during Vite serve and incremental bundles
• replay generated Tailwind CSS into the imported target without overwriting the root shell
• add a reusable 7-case HMR matrix for the CI-compatible uni-app Vite demos across wxss, acss, qss, and ttss
• record explicit exemptions for Taro merged root styles, styleInjector-disabled output, and local-only HBuilderX chains

Verification

• pnpm --filter weapp-tailwindcss exec vitest run test/bundlers/vite-plugin.bundle.unit.test.ts test/bundlers/vite-css-finalizer.unit.test.ts test/bundlers/vite-helpers.unit.test.ts test/bundlers/vite-processed-css-assets.unit.test.ts test/bundlers/vite-remembered-css-replay.unit.test.ts test/watch-hmr-regression.unit.test.ts (371 passed)
• pnpm --filter weapp-tailwindcss build
• pnpm e2e:root-style-shell-hmr (7 passed)
• filtered subpackage multiplatform build regression for mp-weixin/mp-alipay/mp-toutiao in isolated and single cssEntries modes (6 passed)
• pnpm exec vitest run --bail=1 -c ./e2e/vitest.e2e.config.ts e2e/e2e-matrix.test.ts (32 passed)
• targeted ESLint and workflow YAML parse

The broad filtered static run also passed all uni-app checks but retained four existing Taro Vite output failures unrelated to this change.

Release

• reuses the existing Chinese patch changeset .changeset/quiet-walls-serve.md
• no create-weapp-vite bump is required because templates and scaffold behavior are unchanged

[changeset-bot]

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Latest commit: f6672f8

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