Drop the @inspirejs/core/util workaround

[DmitrySharabin]

What

The meta package no longer imports @inspirejs/core/util explicitly.

Why

The plugins package now references each plugin file with a static loader, so import-map/bundler tooling traces the plugins' own dependencies — including @inspirejs/core/util — on their own. The explicit import is redundant.

Note: this relies on the plugins change shipping; the dependency floor is intentionally left at ^3.

Related PRs

Coordinated change across the repos:

• Trace plugin dependencies via static loaders plugins#3 — static plugin loaders (makes deps traceable)
• Let plugins supply their own static import() loader core#2 — core honors the new load loader
• Load markdown-it as a local dependency instead of from a CDN plugins#4 — markdown-it as a local dep

🤖 Generated with Claude Code

[DmitrySharabin]

This PR depends on inspire-js/plugins#3. We can't merge it separately and not break anything.