Display voting metrics in distribution history

[kingpy-bot]

Summary

• add Cycle Distribution History columns for total vote weight, unique voters, and vote count
• load cycle/proposal/vote data through the existing EOS RPC patterns
• avoid mutating the balances array while rendering newest cycles first
• keep metric cells graceful while data is loading or unavailable

Addresses #104.

Checks

• npm run lint (passes with existing repo warnings, 0 errors)
• git diff --check
• Vue script block parse check

Build note

I also tried a Node 14.21.3 build after rebuilding node-sass. The full app build reaches client bundling, then fails on existing dependency-stack issues outside this change: bulma-slider Sass uses math.div with node-sass 4, and vue-simplemde cannot resolve several CodeMirror modules. I did not change dependency files in this PR.