feat: secure room join via room hash in ipfs pubsub chat

[akhileshthite]

https://github.com/AgregoreWeb/website/tree/main/docs/examples/ipfs-pub-sub-chat

Summary: There are two proposed improvements to the current IPFS PUBSUB chat system implementation:

• Create Room with Topic Name (Hashed) and Auto-Join: When creating a room, the user should input a topic name, which will be hashed into a unique identifier (hex hash). The user should immediately join the room upon creation using this hash.

• Join Room with Hash Only: To invite others, they will need to enter the room using only the provided hash. A separate "Join Room" button should be added to allow users to input and join rooms by their hash.

This is a static app, so we can use web crypto api, eg:

async function hashRoomName(roomName) {
    const encoder = new TextEncoder();
    const data = encoder.encode(roomName);
    const hashBuffer = await crypto.subtle.digest('SHA-256', data); 
    const hashArray = Array.from(new Uint8Array(hashBuffer)); 
    const hashHex = hashArray.map(byte => byte.toString(16).padStart(2, '0')).join('');
    return hashHex;
}