fix(eslint): respect custom page extensions in no-html-link-for-pages

[Dishairano]

Summary

• update the
  o-html-link-for-pages rule to use configured page extensions when collecting internal routes
• expose the detected pageExtensions from eslint-config-next so the rule works without manual settings
• add unit fixtures covering .page.tsx files to prevent regressions

Fixes #53473.

Testing

• corepack pnpm --filter eslint-plugin-next test -- --testPathPattern=no-html-link-for-pages.test.ts

[ijjk]

Allow CI Workflow Run

• approve CI run for commit: 4e0534d

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