v4.0.0-beta1

Pre-release of 4.0.0. The codebase is now TypeScript on Lit 3, and the level rings
are drawn by an in-house SVG renderer instead of Chart.js; the bundle is about 30 %
smaller. Rendering, configuration and behaviour are unchanged, with a few deliberate
bug fixes:

• A configured tap_action now takes precedence over per-icon more-info, and
  tap_action: navigate actually loads the target view (#279). If a config relied on
  both a tap_action and implicit per-icon more-info, add link_to_sensors: true to
  keep more-info on the icons.
• German labels for the native 5-level scale (Polleninformation EU, MeteoSwiss,
  IRM KMI) top out at "sehr hohe Belastung" instead of "hohe Belastung" (#277).
• Atmo France days reported as Indisponible show the card's no-data pattern instead
  of an empty green ring.
• Hand-written string-typed YAML values (minimal: "false", days_to_show: "4") are
  now coerced to what they say.

Testing focus for this beta: anything visual (the rings are a new renderer, verified
pixel-identical in our tests), tap actions, and the visual editors. Please report
anything odd against the relevant issue or a new one.

Full details in the CHANGELOG.