Fix outdated references after migration to self-hosted Cloudflare Workers

[Copilot]

The migration to self-hosted Cloudflare Workers left stale references to deleted GitHub Actions workflows and sync endpoints.

Documentation updates:

• Updated workflow badge to reference ci.yml instead of deleted sync.yml
• Replaced deployment section to document Wrangler CLI usage instead of NuxtHub Action
• Documented Nitro scheduled tasks (sync:epochs, sync:snapshot) that replaced GitHub Actions cron jobs

UI cleanup:

• Removed manual sync functionality from app.vue that called deleted /api/v1/sync/sse endpoint
• Replaced with informational note about automatic hourly synchronization via Cloudflare Workers cron

The sync endpoints were removed because synchronization now happens automatically via scheduled tasks configured in wrangler.json:

// server/tasks/sync/epochs.ts - runs hourly via cron trigger
export default defineTask({
  meta: { name: 'sync:epochs' },
  async run() {
    // Fetch and store missing epochs
  }
})

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[onmax]

Merged manually after resolving conflicts