fix(react-native): report correct agent version and set RN peer floor to 0.73

[KishanPRao]

Summary

The SDK stamped a hardcoded 0.0.1 agent version on every report; read it from the package version instead, and set the supported RN floor to 0.73.

Changes

• packages/react-native/src/BacktraceClient.ts: read agentVersion from the package version instead of the hardcoded 0.0.1.
• packages/react-native/package.json: set the react-native peer dependency floor to >=0.73.0 (0.72 crashes on init, 0.73 to 0.83 validated).

Note

agentVersion reads package.json through the react-native/src entry Metro uses, so it is correct at runtime; the lib/ builds resolve the path one level too deep, but RN never loads lib/.

ref: BT-7355

[melekr]

we're pinning "react-native": ">=0.72.0"