Rewrite README with comprehensive API documentation

[msilivonik-sc]

Background

The existing README was a minimal overview with a few usage snippets and external links. It didn't document the full API surface — props, hooks, types, and utilities — making it hard for new users to integrate the library without reading the source code.

Change

• Rewrote the introduction to clearly describe what the package does and link to both the live demo and official Camera Kit docs.
• Added a Quick start section with a minimal working example.
• Documented all component props in tables:
  • CameraKitProvider (7 props including stabilityKey, extendContainer, createBootstrapEventHandler)
  • LensPlayer (15 props with cross-reference to LiveCanvas/CaptureCanvas children pattern)
  • LiveCanvas / CaptureCanvas
• Documented all hooks with signatures, parameter tables, and examples:
  • useCameraKit — full state properties (11) and methods (12)
  • useApplyLens, useApplySource, usePlaybackOptions
• Added Media sources section covering camera, video, and image SourceInput types with options tables.
• Added Handling loading and error states section showing SDK/source/Lens status patterns.
• Added a Full example: Lens switcher with a complete working component.
• Added Utilities table (createConsoleLogger, type guards, CameraRotationOptions).
• Consolidated prerequisites into a concise Requirements block with peer dependency versions.
• Condensed the Development commands section.

Test Plan

• Documentation-only change — no code modified. Verified all documented props, hooks, methods, and types against the source code for accuracy.

[jciereszko-sc]

LGTM