Desktop app: show full filename on hover for truncated file attachment cards

Environment: Claude desktop app (Code tab), macOS.

Problem: When a session has file attachments with long names (e.g. build artifacts like foundational-m365-agent-staging-1.0.0-7b97c24605.zip), the file-card UI truncates the name to fit the box. There is currently no way to see the full filename without downloading the file — hovering shows nothing.

When several attachments share a long common prefix and differ only near the end (versioned builds, per-environment artifacts like ...-staging-... vs ...-prod-...), the truncated cards become indistinguishable, and it's easy to grab the wrong file.

Suggestion: On hover over a file card, show the full filename — a native title tooltip would already solve it; a styled tooltip or middle-ellipsis truncation (keeping the distinctive tail visible) would be even better.

Why it matters: Sessions that produce versioned deliverables routinely attach files whose distinguishing suffix (version, SHA, environment) is exactly the part that gets truncated.