Replaces the per-leaf @Shared(.repositorySettings(rootURL)) subscriptions from the previous attempt with a reducer-managed dictionary on RepositoriesFeature.State. The old approach created a fresh @Shared wrapper instance per call inside hot-path methods (orderedShelfBooks, toolbarNotificationGroups, the canvas card loop), which on cache miss triggered a settingsFile write that notified all settingsFile subscribers, re-ran view bodies, re-built the wrappers, and looped — pegging CPU at 90%+ on launch. Now the flow is: - RepositoriesFeature.State gains `repositoryCustomTitles: [Repository.ID: String]`. - Four new actions manage the dict: refreshAllCustomTitles (full batch reload, runs in a reducer effect that's safe to read @Shared from), refreshCustomTitle(URL) (single-repo refresh), customTitlesLoaded(dict), customTitleUpdated(id, title?). - AppFeature wires the triggers: it forwards `.repositories(.delegate(.repositoriesChanged))` to `.repositories(.refreshAllCustomTitles)`, and forwards `.settings(.repositorySettings(.delegate(.settingsChanged(url))))` to `.repositories(.refreshCustomTitle(url))`. - All display sites read the dict statically: - RepoDisplayName is now a pure-props view (no @Shared). - Sidebar (RepoHeaderRow/RepositorySectionView), settings list, settings detail nav title, and RepositoryDetailView take the resolved custom title as a String parameter. - ShelfBook.orderedShelfBooks and toolbarNotificationGroups accept a customTitles dict; the shelf spine, toolbar notifications popover, and canvas card all pass `state.repositoryCustomTitles`. Tests cover the dict-mutation actions (customTitlesLoaded/customTitleUpdated state guards) and parameterized model methods (orderedShelfBooks + toolbarNotificationGroups override + fallback). The previous attempt's hot-path tests are dropped — the methods are now pure with no @Shared dependency to mock.