PARTIAL SAVE: writes ONLY the 'FeatureTracking' field of TitlePublicConfigurationModel; all other v1/v2 fields stay untouched. Feature tracking — which CONCRETE actions are recorded as their own line in the player's FeatureUsage, on top of the default per-module tracking. Entries look like "Character:EquipItems" (module name from the route + the module's action name). Purely an analytics setting: it makes those actions selectable as steps in custom funnels (Analytics → Funnels). Tracking starts when an action is added — there is no data for the past, because the action was not recorded then. Capped at 40 entries: every tracked id becomes a key in the player document, which is read on every request.