Add session calendar, ride statistics, and gearing fixes

[ridecontrol]

What changed

• Add linkable Calendar, List, and Statistics tabs to the Sessions tray, including month navigation through the date=YYYY-MM URL parameter.
• Add an incrementally maintained IndexedDB analytics cache with all-time totals, personal bests, and weekly, monthly, yearly, and complete-history trends.
• Virtualize large session histories and backfill existing saved rides without rescanning full telemetry when the tray opens.
• Default bulk session downloads to TCX and remember the selected FIT/TCX format locally.
• Keep hard virtual gears meaningfully loaded on descents and fix workout cards so the first click selects them instead of only repositioning the list.
• Document the new frontend behavior.

Why

Saved-session history needed to remain responsive as ride counts grow, support direct links and browser navigation, and provide useful long-term training summaries without repeatedly processing every recorded sample. The gearing and workout-card fixes address issues found during real rides and route selection.

Validation

• bun run ci
• Biome and Tailwind diagnostics clean with zero warnings
• 323 unit tests passing
• TypeScript validation passing
• Production Vite/Cloudflare Worker build passing
• Calendar, tabs, URL history, and persisted download format verified in the running frontend