dsh-remote 0.4.0: edge auth – slaves log in to an auth proxy in front of the master

- lib/edge-auth.mjs: basic / bearer / oauth2 client_credentials (Authentik M2M) /
  custom headers (Cloudflare Access), proxy session cookie jar, retry with fresh
  token, clear edge-refusal vs DSH-refusal errors
- link + enroll go through the edge; master.edgeAuth stored at pair time,
  secrets as DSH credential refs only; config edgeAuth override
- /dsh-remote/edge-auth: show/change/probe; Settings UI section + pair form
- pair.mjs / install-mac.sh: --edge … flags, secrets prompted via /dev/tty
- tests: fake Authentik-like proxy for all modes + WebSocket through the edge

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@local/dsh-remote",
-  "version": "0.3.0",
+  "version": "0.4.0",
   "description": "Claude-Desktop-style remote control for DSH: master/slave link, every device's sessions on every device (/r/<device>/), plugin + config sync with opt-in secrets.",
   "private": true,
   "type": "module",