feat(media): add UI prototype wireframes to media gallery - classify .wireframe.json diagrams as wireframe category with canvas preview - link wireframe companion files to note references and deduplicate preview PNGs - add UI Prototypes category filter and single-line sidebar layout - clean up unused imports and lint warnings

feat(media): add UI prototype wireframes to media gallery - classify .wireframe.json diagrams as wireframe category with canvas preview - link wireframe companion files to note references and deduplicate preview PNGs - add UI Prototypes category filter and single-line sidebar layout - clean up unused imports and lint warnings #198