implement rate limiting (10/min per sender)

src/lib/client.js

···
 		this.pending = new Map();
 		this.accepted = new Set();
 		this.blocked = new Set();
-		this.rateLimit = 10;
 		this.accessToken = null;
 	}
 

src/lib/components/PdsPanel.svelte

···
 	<div class="role-label {role}">{role}'s pds</div>
 	<h2>{pds.handle}</h2>
 	<div class="did">{pds.did}</div>
-	<Tooltip text="max messages per minute from any accepted sender">
-		<div class="subtitle">rate: {pds.rateLimit}/min</div>
-	</Tooltip>
 
 	<div class="requests">
 		<Tooltip text="first contact requires acceptance (like DM requests)">
···
 		font-size: 9px;
 		color: #383838;
 		font-family: monospace;
-		margin-bottom: 4px;
-	}
-
-	.subtitle {
-		font-size: 10px;
-		color: #444;
 		margin-bottom: 1rem;
 	}