[Easy] Add prefers-reduced-motion guard to MCPPairingPanel connection indicator animation

[hoainho]

Context

The MCP pairing panel (see task 2.9 in openspec/changes/mcp-server-v1/tasks.md) ships with a pulsing animation on the "● Connected" indicator. Users who set prefers-reduced-motion: reduce in OS or browser should see a static version.

Where to look

• File: src/panel/components/MCPPairingPanel.tsx
• CSS: wherever the indicator pulse animation is defined (likely a CSS file imported by the panel)

Expected outcome

• CSS uses @media (prefers-reduced-motion: reduce) to disable the pulse animation
• Static indicator still clearly communicates connection state (color is enough — green/red/grey)

Estimated effort

S (1–2h)

How to claim

Comment @hoainho I will take this to claim. PR within 10 days or unclaimed.

Acceptance criteria

• Manual test: enable Reduce Motion in macOS Accessibility settings; reload extension; indicator does not animate
• No regression on default (animation still works when reduce-motion is not set)