feat(evaluators): gallery card tweaks

[rickarize]

👾 AUTOMATED REPORT:

Stacked on #15686. Tweaks to the project evaluator gallery cards:

• Flatten the gallery into a single scrolling stack of titled, anchorable use-case sections instead of Recommended/All-evaluators category filtering; the use-cases sidebar now tracks scroll position instead of filtering cards.
• Page the category carousel by full groups instead of one card at a time.
• Declutter the evaluators empty state (drop the redundant title/PageHeader) and keep the gallery promo visible under the table when a project has fewer than 15 evaluators.
• Add metadata badges to gallery cards, with a tooltip on the evaluation-target badge.
• Add an expandable prompt preview to the gallery card details panel, and trim the card description to the detailed variant only.
• Unify the evaluator kind badge with EvaluatorKindToken, and fix Token's line-height, which only coincidentally matched at the "M" size.
• Double-click (or activate via keyboard) a selected template card to jump straight to customize.
• Replace the gallery's scratch-start actions with a single, reusable AddProjectEvaluatorMenu — supporting a custom label, variant, and gallery-item visibility so the same menu works on both the plain table and the gallery — and nest scratch creation under the gallery route so closing the modal returns to the gallery instead of the plain table.
• Clarify gallery/menu wording: "Browse eval gallery", "Duplicate existing", "Use existing", "Target"/"Annotation values".

[claude]

This assertion is now unsatisfiable, so can create, edit, and delete a span LLM evaluator will fail here.

Decluttering the empty state removed the <PageHeader /> from the empty-state branch of ProjectEvaluatorsPage.tsx, replacing it with a plain <Text> blurb + AddProjectEvaluatorMenu:

phoenix/js/app/src/pages/project/evaluators/ProjectEvaluatorsPage.tsx

Lines 101 to 107 in f4309fd

	>
	<Text size="S" color="text-700">
	Evaluators read span inputs, outputs, retrieved documents, and
	tool calls, then return labels or scores you can filter, chart,
	and alert on.
	</Text>
	<AddProjectEvaluatorMenu

PageHeader was the only thing rendering a role=heading node named exactly "Evaluators" on this route — it wraps a string title in <Heading level={1}>. Everything else named "Evaluators" here is a tab or a link, and ProjectEvaluatorsEmptyState renders no heading. The test creates a fresh project (asserted below to have 0 evaluators), so it hits exactly the branch whose header was removed.

The two sibling assertions in this block were updated for the "Browse eval gallery" rename — this one looks overlooked. Retargeting it at the new description text works (that string is unique in js/app/src):

Suggested change

	page.getByRole("heading", { name: "Evaluators", exact: true })
	).toBeVisible();
	page.getByText("Evaluators read span inputs")
	).toBeVisible();