#3960 feat(service,host): follow the sidebar's sections and pins over Neon Realtime

The sidebar's sections and repository pins move onto the live layer. Service and host are in one PR because both are small. Stacked on #3956.

• New live procedure live.sidebar: three statements, sections, entries and pins, with the same rows and access rule as listTaskSections and listRepositoryPins.
• Reader: sidebarOfLiveRows (sidebar-live.ts) orders them as the held reads do.
• Host: follows them on liveRows, as it follows the workspaces, and writes taskSections and repositoryPins onto the view. The pins and sections reads inside every TASKS_REFRESH are gone; a write still draws the service's answer at once.

Tests

• PGlite parity: the section owner, a teammate and an outsider.
• Procedure test.
• Immutability check.
• compose-tasks: one seal across refreshes, and another Mac's section and pin pushed in order.

Made with Luke