v1.0.0

feat(v1.0): app-wide instance selection, server ping, and UI polish

Phase 04-02/04-03: Mods and Shaders tabs now read selectedInstanceId from
SelectedInstanceContext instead of maintaining local dropdowns. Replaced
select elements with compact instance header + "← Change" nav button.
Added Sidebar Play button that launches the selected instance directly,
with loading state and inline error display.

Server ping (SLP): instances with a default server now show the server's
favicon as their card icon and MOTD as a subtitle line. Raw TCP Minecraft
Server List Ping protocol implemented in main process; errors are swallowed
so offline servers fall back to the globe emoji gracefully.

UI improvements:
- App icon (BH logo) in title bar replacing pickaxe emoji
- Sidebar width 200px → 300px
- Instance card edit button 32px → 44px, circular, visible
- Removed per-card play buttons (redundant with sidebar Play)
- Player avatars via mc-heads.net with onError fallback in title bar and settings
- Sidebar instances refresh on selectedInstanceId change (fixes stale list bug)

Bump version 0.7.0 → 1.0.0

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>