Dashboard `CopyButton`: the "copied ✓" timer is never cleared

[chhhee10]

Description

CopyButton (app/components/copy-button.tsx:37) fires
setTimeout(() => setCopied(false), 2000) on every copy with no stored id and no cleanup. It
assumes exactly one click at a time and that the component stays mounted for the full 2s.

Steps to Reproduce

1. Rapid re-click: click Copy at t=0 (timer A, reverts at 2.0s). Click again at t=1.5s
   (copied → true, timer B). Timer A still fires at t=2.0s and flips the checkmark back to the
   copy icon 0.5s early, contradicting the just-shown feedback.
2. Unmount mid-window: copy a row's value, then let the sessions table re-paginate/filter
   (unmounting that row) before 2s elapses → setCopied runs on an unmounted component →
   React "state update on unmounted component" warning; the leaked timer pins text in its closure.

Expected Behavior

Only the latest timer should control the revert; no state updates after unmount.

Failproof AI Version

0.0.14-beta.1

Node.js / Bun Version

Bun 1.3+

Operating System

macOS

Additional Context

Store the timeout id in a useRef, clearTimeout it before re-arming, and clear it in a
useEffect(() => () => clearTimeout(ref.current), []) cleanup. (Bonus: the <button> is also
missing type="button" at :53.)