Removes what would block a later switch to Vue's vapor mode:
`vue-chartjs` and the `SvgIcon` render function are virtual DOM
components, and `v-memo` has no vapor equivalent. This does not adopt
vapor mode, which will be stable in upcoming Vue 3.6.
`vue-chartjs` was a thin wrapper over chart.js, so a local
`ChartCanvas.vue` replaces it. Chart data and options move into computed
values to keep their object identity, which is what `v-memo` was
compensating for.
`chartjs-adapter-dayjs-4` is moved first-party, just ~40 lines that are
easy to maintain.
silverwind