0.2.0

Demo-ready release. Adds everything past 0.1.0's read + write surface:

Bridge:
- Base58 decoder + DecodeToHex helper
- BridgeOutAsync on VelocityClient
- WaitForProofAsync polling helper

Streaming:
- SseFrame, SseFrameParser, SseDownloadHandler
- StreamBridgeEventsAsync as IAsyncEnumerable<BridgeEvent>
  (non-WebGL)

Inspector components:
- VelocitySettings ScriptableObject
- VelocityClientBehaviour MonoBehaviour
- BridgeEventListener MonoBehaviour with UnityEvent<BridgeEvent>

Samples:
- Samples~/BasicDemo with BasicDemoController

Documentation~/index.md landing page. README + CHANGELOG expanded.

Deferred: WebGL SSE, auto-reconnect inside StreamBridgeEventsAsync,
player-signed actions, Solana-side mint_from_proof interaction.