Description (replace the blank template with this):

• I have read the Contributing Guide.
• I have added information to docs/ if required so people know about the feature.
• I have filled in the "Changes" section below.
• I have filled in the "How did you test this code" section below.

Changes

Closes #4239

A feature permalink (?feature=<id>) is opened by the matching FeatureRow's
own effect, but rows are only rendered for the current page of results. When the
linked feature lives on a later page no row exists, so the permalink was a no-op
and the user simply landed on the first page.

This adds a FeaturePermalinkHandler that, when the linked feature is not
present on the current page, fetches the feature and its environment feature
state and renders a single hidden FeatureRow — reusing the existing
panel-opening logic rather than duplicating it.

How did you test this code?

Manually:

1. Open a project/environment with more than 50 features (so the list paginates).
2. Copy a permalink to a feature that lives on the second page or later, e.g.
   /project/<id>/environment/<key>/features?feature=<id>&tab=value.
3. Open the link in a new tab — the feature panel now opens directly, instead of
   landing on the first page with nothing open.
4. Confirm permalinks to features on the first page still open as before.

Also ran npm run typecheck and eslint on the changed files (no new errors).