fix(streaming): ICE trickle serialisation, kind propagation, DataChan…

[imaTik0]

…nelCryptor

ICE trickle candidate serialisation (StreamApiNative):

• Replace JSON.stringify(candidate) with serializeCandidate() which explicitly reads all 15 RTCIceCandidate fields; toJSON() only emits 4 fields causing bridge-side parse failures for candidates with extension fields

RTCRtpScriptTransform kind propagation (WebRtcClient):

• Pass kind: track.kind to every encode/decode transform option so the worker selects the correct header-size table (audio=1B, video key=10B, delta=3B) instead of always defaulting to video; fixes silent audio encryption

DataChannelCryptor:

• Use getEncryptionExternalKeyId() for the wire key ID and resolveKeyId() when passing to CryptoFacade; separates wire format from internal registry key
• Extract GCM_TAG_LENGTH_BYTES = 16 named constant (was magic number)
• Move Logger to class field (avoids per-call allocation)
• Rename keyId → externalKeyId throughout for clarity
• Add JSDoc on encrypt/decryptFromWireFormat