Add zoomable interactive wrappers for indexed and time-series charts #2

Problem\nPackage consumers can scroll some charts today, but they still need to drop to raw Swift Charts for true zoomable navigation. This is especially painful for analytics and time-series exploration where detailed inspection requires panning and zooming over the visible domain.\n\n## Proposed slice\n- extend the existing scrollable/interactive wrapper family instead of creating a separate chart family\n- add true zoom + pan behavior for indexed and time-series charts\n- expose gesture-driven interaction plus public binding/state control\n- optimize the first version for a single chart at a time\n- keep the public state shape future-ready for shared multi-chart synchronization\n\n## Acceptance criteria\n- public navigation/window state exists for indexed and time-series charts\n- shared coordination logic clamps and updates zoom/pan state predictably\n- existing scrollable wrappers can adopt the new zoom/navigation API without regressing scroll behavior\n- focused tests cover state transitions, wrapper configuration, and binding behavior\n- README and changelog document the new interaction surface\n\n## Out of scope\n- new parallel zoom-specific wrapper families\n- full multi-chart synchronization\n- brush/minimap/navigator panes\n- unrelated interaction or maintainability refactors