feat: add schedule components

[glitchedmob]

Adds the standalone Svelte schedule UI layer so later CMS pages can render the MethodConf schedule without pulling in route conversion work.

• Ports the schedule block, responsive track grid, session cards, and local disclosure behavior to Svelte 5.
• Preserves the CMS-owned grid areas, null cells, track slicing breakpoints, swipe controls, speaker avatar image behavior, and More/Less keyboard state.
• Adds narrow schedule helper types and SSR/unit coverage for grid IDs, breakpoints, sorting, missing descriptions, speaker links, and empty data.