v0.21.3

Added

• README logo. A small eye mark (light/dark SVG variants under
  assets/, swapped via prefers-color-scheme) now heads the
  README — a nod to the name itself ("dekko" is British slang for a
  look or glance).
• MCP Registry metadata. Added server.json and an mcp-name: io.github.aahlijia/dekko marker in the README so dekko can be
  published to the official MCP
  Registry.