v0.6.4 — Chain-edge crash fix and stale UI state

Ontheia 0.6.4 — Chain-edge crash fix and stale UI state

A chain edge that carries no map field is valid per the chain spec, which
requires only from and to. Such an edge previously crashed the run with
"Cannot convert undefined or null to object"; it now injects no data and serves
only as a dependency the graph validator uses for cycle and DAG checks. Steps
keep running in array order, so a map-less edge is a no-op for data flow.

The web UI fixes three stale memo and callback hooks. Switching the primary
agent no longer keeps the wrong chain options cached; localized summary dates
refresh when the language or timezone changes; and the display-name handler and
timezone in user settings no longer go stale.

The ESLint error backlog is cleared to zero for both the host and the web UI,
and CI now runs lint, build and test on every pull request and push to main.