Anna/prod 4531/gradient on agentic chat windows should be subtler

[wailingwombat]

Test Plan

Checklist

• If required, I have updated the Plural documentation accordingly.
• I have added tests to cover my changes.
• I have added a meaningful title and summary to convey the impact of this PR to a user.

Plural Flow: console

[linear]

PROD-4531 gradient on agentic chat windows should be subtler

[greptile-apps]

Greptile Summary

This PR makes two minor visual polish changes to agentic chat UI components. No logic, data, or behavioural changes are introduced.

• AIAgentRunMessages.tsx: Reduces the bottom-stop opacity of the GradientWrapperSC background gradient from 0.13 to 0.05, making the subtle purple tint nearly imperceptible.
• ClusterUpgradeAgentFlyover.tsx: Changes the ChipSeverity for both Pending and InProgress cluster-upgrade statuses from 'info' to 'neutral', switching those chips from the blue info palette to a neutral/greyed palette while keeping the loading spinner behaviour intact.

Confidence Score: 5/5

• This PR is safe to merge — both changes are purely cosmetic and carry no runtime risk.
• Both changes are isolated, intentional UI tweaks (gradient opacity and chip colour palette) with no impact on logic, state, or data handling.
• No files require special attention.

Important Files Changed

Filename	Overview
assets/src/components/ai/agent-runs/details/AIAgentRunMessages.tsx	Gradient opacity at the bottom of the chat window reduced from 0.13 to 0.05, making the purple tint subtler. No logic changes.
assets/src/components/cd/clusters/ClusterUpgradeAgentFlyover.tsx	Chip severity for Pending and InProgress cluster upgrade statuses changed from 'info' to 'neutral'. The loading spinner behaviour is unchanged.

_{Last reviewed commit: 567235c}