chore(release): bump to v2.28.2

Changelog:

- console.debug in src/unity-editor-bridge.js (queue submit) and
  src/tool-tiers.js (lazy-load) routed to console.error so stdout stays
  reserved for MCP JSON-RPC framing. Fixes transport-closed errors on
  strict MCP clients (Codex CLI); invisible on lenient clients
  (Claude Desktop / Claude Code). Closes #11.