feat(cli): connect via relay using pairing offer URL (#639)

Pass `--host https://app.paseo.sh/#offer=...` (or `PASEO_HOST=...`) to
any CLI command and the connection routes through the relay with E2EE,
the same way the mobile and desktop apps connect. Same `paseo daemon
pair` link the app already accepts — no new pairing flow.

Closes #181

packages/app/src/utils/daemon-endpoints.ts

@@ -1,4 +1,3 @@
-import { Buffer } from "buffer";
 import {
   buildDaemonWebSocketUrl,
   buildRelayWebSocketUrl as buildSharedRelayWebSocketUrl,
@@ -9,6 +8,8 @@ import {
   type HostPortParts,
 } from "@server/shared/daemon-endpoints";
 
+export { decodeOfferFragmentPayload } from "@server/shared/connection-offer";
+
 export type { HostPortParts };
 
 export {
@@ -19,17 +20,6 @@ export {
   parseHostPort,
 };
 
-function decodeBase64UrlToUtf8(input: string): string {
-  const base64 = input.replace(/-/g, "+").replace(/_/g, "/");
-  const padded = base64.padEnd(base64.length + ((4 - (base64.length % 4)) % 4), "=");
-  return Buffer.from(padded, "base64").toString("utf8");
-}
-
-export function decodeOfferFragmentPayload(encoded: string): unknown {
-  const json = decodeBase64UrlToUtf8(encoded);
-  return JSON.parse(json) as unknown;
-}
-
 export function buildRelayWebSocketUrl(params: { endpoint: string; serverId: string }): string {
   return buildSharedRelayWebSocketUrl({ ...params, role: "client" });
 }