0.2.1 - Channel change

The static between channels is now a choice, and the README walks in by stages.

Features:

• Channel change setting - tuner.cut picks what covers a channel change: static (RF tuner snow, the default), black (the blanked raster of a later cable box), or none (a hard cut). A "Channel change" select in the control room's Channels panel sets it; a note explains that static and black also give a video channel a beat to load its first frame.
• README in natural stages - Quick start, then the control room, then channels, then channel 82, then the config.json reference, then the CRT notes. A new Channels-panel screenshot shows three channels on the dial and the tuner settings.

Under the hood:

• The schema is the single authority for tuner.cut; an unknown value falls back to static.
• tuneToIndex reads a CUTS table (cover before the swap, cover after so the new channel has its first frame up) with a try/finally so a throw never strands the tuner.
• New #tuner-blank layer for the black cover, tinted with the theme's ink color.
• Control room fix: the "on the dial" toggle label no longer wraps to three lines.
• Tests: 38 server + 53 browser-harness, still dependency-free Node 18+, no build step.