Chart property names containing `/` failed because per-key flat-file storage interpreted the slash as a filesystem path separator, and any move to line-based storage would silently truncate multi-line values. A new `PropertyMap*` helper family in `common` persists each map as a single JSON file so both `/` in keys and `\n` in values round-trip losslessly. Chart overrides move to `chart-overrides.<chart>` and an idempotent `TriggerInstall` migration rewrites any legacy `chart.<chart>.<key>` files into the new layout. The deprecated `scheduler-k3s:set --global chart.*` form is rerouted through the same map storage so it does not silently orphan writes. Closes#8717.