Genericized dashboard example

[lappat]

The engine ships with one worked example (examples/demo-campaign/combat.html)
but no dashboard — the thing most tables actually open first each session.

Goal: a generic campaign dashboard following the same config-driven
pattern as the combat tracker example — session/chapter counters, group
funds, a moral/status tracker, quick links out to other tools — reading
everything from window.FarholdConfig / the campaign JSON files, no
hardcoded roster or lore.

See docs/ARCHITECTURE.md for the three-tier config pattern to follow,
and examples/demo-campaign/combat.html for a concrete reference of
what "config-driven" looks like in this codebase.