fix: Mark react-native-nitro-modules peer dependency as optional

[mrousavy]

Problem

Semver ranges never match pre-release versions unless a comparator shares the same major.minor.patch tuple and carries a pre-release tag. So the "react-native-nitro-modules": "*" peer range does not match a version like 0.37.0-beta.0:

range	0.36.5	0.37.0-beta.0	0.37.0	0.38.0-beta.0
*	yes	no	yes	no
>=0.0.0-0	yes	no	yes	no
>=0.37.0-0	no	yes	yes	no

Because the peer is required, bun satisfies it itself by installing a second, stable copy of react-native-nitro-modules nested inside this library. An app testing a Nitro pre-release then builds native against the pre-release while Metro bundles the stable JS, and Nitro throws at startup:

Nitro was installed twice: once with native version 0.37.0-beta.0 and once with JS version 0.36.5.

Builds stay green - only runtime catches it.

Fix

Mark the peer optional, so the consuming app is the sole decider of the Nitro version. No range can express "anything, including future pre-releases" (>=0.37.0-0 just moves the breakage to 0.38.0-beta.0), so this has to be resolution behaviour rather than a cleverer range.

"peerDependenciesMeta": {
  "react-native-nitro-modules": { "optional": true }
}

Upstream fix in the Nitro template + docs: margelo/nitro#1516

Trade-off

optional: true also suppresses the missing peer warning. Acceptable: a Nitro Module without react-native-nitro-modules fails loudly at build time (autolinking cannot find the pod / Gradle project), and version mismatches are caught by Nitro's runtime guard - strictly stronger than an install-time range check.

The example app declares react-native-nitro-modules directly, so it is unaffected.