Add release automation (#521)

## Description
Add a script called in the release automation workflow.

Example PR:
https://github.com/fishjam-cloud/release-test-mobile-client-sdk/pull/3

## Motivation and Context
Speed up the release.

Author: ostatni5

.tool-versions

@@ -0,0 +1 @@
+nodejs 18

release-automation/bump-version.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+set -e
+
+# NOTE:
+# This script prepares a release by creating a `release-<version>` branch
+# and updating package versions (root `package.json` and the
+# `@fishjam-cloud/react-native-client` workspace). It does NOT commit or
+# push the changes to the remote repository. Committing and pushing (and any
+# additional CI/workflow steps) are expected to be handled by the caller or
+# the surrounding release automation workflow that invokes this script.
+# This will be called by the release workflow in @fishjam-cloud/release-automation.
+#
+# Usage: ./bump-version.sh <version>
+
+VERSION="$1"
+
+if [ -z "$VERSION" ]; then
+    echo "Usage: $0 <version>"
+    exit 1
+fi
+
+# Validate semantic version format (X.Y.Z)
+if ! [[ "$VERSION" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+    echo "Error: Version must be in format X.Y.Z"
+    exit 1
+fi
+
+# Create release branch
+BRANCH_NAME="release-$VERSION"
+git checkout -b "$BRANCH_NAME"
+
+# Update root package.json
+if [ -f package.json ]; then
+    echo "Enabling corepack..."
+    corepack enable
+    corepack yarn install
+    corepack yarn version "$VERSION"
+    echo "Updated root package.json to $VERSION"
+else
+    echo "Root package.json not found!"
+    exit 1
+fi
+
+# Update react-native-client package
+corepack yarn workspace @fishjam-cloud/react-native-client version "$VERSION"
+echo "Updated react-native-client to $VERSION"
+
+echo "✅ Version bump complete for $VERSION"
+echo "BRANCH_NAME:$BRANCH_NAME"