🚪 fix: Gate Artifacts Toggle on Agent Capability Flag

[serhiizghama]

Problem

Fixes #13659.

When the artifacts capability is enabled, pinned in the chat input, and then disabled again, the artifacts toggle stays pinned and visible. Unlike the other capability toggles, Artifacts.tsx never checks the agent capabilities config, so it keeps rendering regardless of whether the capability is on.

Steps to reproduce:

1. Enable the artifacts capability.
2. Pin Artifacts in the chat input.
3. Disable the artifacts capability.
4. The artifacts toggle remains pinned.

Solution

Gate the component on artifactsEnabled from useAgentCapabilities, exactly how the sibling capability toggles already work:

• Skills.tsx → skillsEnabled
• FileSearch.tsx → canUseFileSearch
• CodeInterpreter.tsx → canRunCode

const { artifactsEnabled } = useAgentCapabilities(
  context?.agentsConfig?.capabilities ?? defaultAgentCapabilities,
);

if (!artifactsEnabled) {
  return null;
}

The fallback to defaultAgentCapabilities (which includes artifacts) preserves current behavior when no config is present.

Note: the issue suggested gating on PermissionTypes.ARTIFACTS / useHasAccess, but there is no ARTIFACTS permission in the permission system — artifacts is controlled as an agent capability, not a granular permission. Matching Skills.tsx's capability check is the correct mechanism here.

Testing

1. With artifacts in the agent capabilities, the toggle renders and can be pinned as before.
2. Remove artifacts from the capabilities (or disable it in the admin config) — the toggle no longer renders, even when previously pinned.
3. With no agentsConfig, the default capabilities still include artifacts, so the toggle behaves as it does today.