Lit components

Use Lit's standard decorators with TypeScript auto-accessors.

• Import decorators from their individual lit/decorators/<name>.js modules.
• Declare public reactive inputs with @property(...) public accessor and internal render state with @state() private accessor.
• Initialize accessors inline when they have defaults. Use a definite-assignment assertion for required inputs supplied by the host.
• Use { attribute: false } for object or array inputs that must not map to HTML attributes. Specify type when an attribute needs Lit conversion.
• Do not use the legacy static properties plus declare pattern for reactive members, or enable experimentalDecorators/legacy class-field semantics.
• Verify the component with its package compile, lint, unit tests, and focused browser tests when behavior or rendering changes.