[swarnendusahu10-dotcom]

Summary

Closes #1105

When multiple EmbeddedChat instances (e.g. Sales Bot and Support Bot, or multi-tenant widgets) co-exist on the same domain, logging into one instance previously overwrote the authentication session of the other because the localStorage key was hardcoded to 'ec_token' in packages/react/src/lib/auth.js.

This pull request introduces host-scoped namespaced token storage keys with an opt-in tokenStorageKey prop override and automatic backward-compatible session migration.

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Key Changes

1. Dynamic Namespaced Storage Keys (packages/react/src/lib/auth.js):

   • Refactored getTokenStorage(secure, key) and local storage helpers to accept a configurable storage key.
   • Preserves asynchronous function signatures.
   • Seamless backward compatibility: if a namespaced key is empty, getTokenLocalStorage falls back to and migrates any existing legacy 'ec_token' session so existing users are never logged out upon upgrading.

2. Host-Scoped Resolution & Memoization (packages/react/src/views/EmbeddedChat.js):

   • Automatically scopes the default storage key to ec_token_${normalizedHost}, ensuring different servers maintain completely independent sessions.
   • Crucially avoids room-based scoping (roomId), ensuring that switching channels within the same chat instance does not log the user out.
   • Adds an optional tokenStorageKey prop with PropTypes coverage for integrators needing custom instance isolation on the same host.
   • Wraps getTokenStorage(secure, storageKey) in useMemo to eliminate unnecessary function recreations and prevent redundant RCInstance re-renders.

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Verification

• Verified cross-instance session isolation: logging into Instance A (https://sales.example.com) does not overwrite Instance B (https://support.example.com).
• Verified room navigation: switching rooms within the same host preserves authentication.
• Verified backward compatibility: existing sessions saved under legacy 'ec_token' migrate seamlessly without user intervention.
• Formatted with Prettier (npx prettier --check).
• Clean monorepo build with npm run build (dist/cjs and dist/esm generated without errors).