feat(reactotron-react-native): track Expo expo/fetch in the networking plugin

[ShanavasPS]

Please verify the following:

• yarn build-and-test:local passes
• I have added tests for any new features, if relevant
• README.md (or relevant documentation) has been updated with your changes

Describe your PR

Closes #1612 .

Problem

Expo SDK 56 installs expo/fetch as the default globalThis.fetch. expo/fetch is backed by a native module and bypasses XMLHttpRequest, so the networking plugin's XHRInterceptor never sees it — on Expo SDK 56+ the plugin silently misses all fetch traffic.

(For context, the existing XHRInterceptor only covers React Native's XHR-backed fetch. The same blind spot affects other XHR-based network inspectors on Expo SDK 56+.)

Solution

Add a FetchInterceptor that mirrors XHRInterceptor's shape (set*Callback / enableInterception / disableInterception) and wraps the global fetch only when it is the expo/fetch builtin, detected via Symbol.for("expo.builtin"). React Native's XHR-backed fetch is left to XHRInterceptor, so there is no double-reporting. The networking plugin wires Reactotron into it in onConnect, gated by a new ignoreExpoFetch option.

Care was taken to keep this safe for expo/fetch's streaming model:

• The wrapper returns the original Response immediately and reads the body off a clone, asynchronously — the caller is never blocked and streaming bodies stay intact.
• text/event-stream (and the existing image content types) are never cloned/read, so streaming responses aren't buffered.
• Request URL/method/header parsing for the Request/URL/string argument forms is handled in the interceptor; query-param parsing, content-type policy, and timing stay in the plugin (matching the XHR path).

Files

• lib/reactotron-react-native/src/fetch-interceptor.ts — new, mechanism only (mirrors xhr-interceptor.ts)
• lib/reactotron-react-native/src/fetch-interceptor.test.ts — unit tests (no-op off Expo, wrap/callbacks, rejection, no double-wrap, restore on disable)
• lib/reactotron-react-native/src/plugins/networking.ts — wire in FetchInterceptor, add ignoreExpoFetch option
• docs/plugins/networking.md — document expo/fetch support and ignoreExpoFetch

Notes / known limitations

• Detection is by symbol, so it is a no-op on non-Expo runtimes and on SDKs where globalThis.fetch is not expo/fetch.
• Only globalThis.fetch is wrapped. Code that does import { fetch } from 'expo/fetch' and captures the reference directly bypasses this (as it does the XHR interceptor); the global wrap covers the common case.
• Interception is installed in onConnect, so requests fired before Reactotron connects aren't captured.