docs+plugin: HTTP-only transport cleanup, install guide, review fixes

- docs/install.md: new end-to-end guide for non-technical users
  (gateway install, app install, LAN/TLS/remote connection, push,
  options, troubleshooting); docs/setup.md now points to it
- README: new 'Install the gateway' section; pairing section updated
  for HTTP transport (8791, QR scan on Android)
- rename IRIS_WS_HOST -> IRIS_HTTP_HOST (clean rename, no compat
  fallback); drop dead DEFAULT_PORT=8790
- setup.py: advertise https:// in the printed/QR server URL when
  IRIS_HTTP_CERT is set
- ws_probe.py/e2e.py: default --url http://127.0.0.1:8791, env
  IRIS_WS_URL -> IRIS_HTTP_URL, honor explicit port + https scheme
- plugin.yaml: IRIS_HTTP_* env names, description no longer says
  'WebSocket server'
- docs 03/09/12/19: fix stale WS-era refs (ws_server.py cites,
  8790 smoke test, WSS->HTTPS, 'HTTP fallback' reframed as the
  only transport)
- AGENTS.md: symlink name android -> iris (matches actual install)
- test: adapter reads IRIS_HTTP_HOST/CERT/KEY from env; legacy
  IRIS_WS_* names are not consulted (95/95 pass)

gateway-plugin/plugin.yaml

@@ -4,9 +4,9 @@ kind: platform
 version: 0.1.0
 description: >
   Native Android / Desktop client gateway adapter for Hermes Agent.
-  Runs a WebSocket server inside the gateway; the app connects with a
-  pairing token. Supports streaming, reasoning, structured tool events,
-  channels/threads, media, FTS5 search, and FCM/ntfy push.
+  Runs an HTTP server (optional TLS) inside the gateway; the app connects
+  with a pairing token. Supports streaming, reasoning, structured tool
+  events, channels/threads, media, FTS5 search, and FCM/ntfy push.
 author: Iris x Hermes
 # ``requires_env`` / ``optional_env`` entries are surfaced in the
 # ``hermes config`` / ``hermes gateway setup`` UI via the platform-plugin
@@ -17,13 +17,13 @@ requires_env:
     prompt: "Iris pairing token"
     password: true
 optional_env:
-  - name: IRIS_WS_HOST
-    description: "WS bind host (default 127.0.0.1; use 0.0.0.0 for LAN)"
-    prompt: "WS host"
+  - name: IRIS_HTTP_HOST
+    description: "HTTP bind host (default 127.0.0.1; use 0.0.0.0 for LAN)"
+    prompt: "HTTP host"
     password: false
-  - name: IRIS_WS_PORT
-    description: "WS port (default 8790)"
-    prompt: "WS port"
+  - name: IRIS_HTTP_PORT
+    description: "HTTP port (default 8791)"
+    prompt: "HTTP port"
     password: false
   - name: IRIS_HOME_CHANNEL
     description: "Default chat id for cron/notification delivery (default: default)"
@@ -61,11 +61,11 @@ optional_env:
     description: "ntfy auth token for a private topic (trust boundary)"
     prompt: "ntfy auth token"
     password: true
-  - name: IRIS_WS_CERT
-    description: "TLS cert path for WSS (optional)"
-    prompt: "WSS cert"
+  - name: IRIS_HTTP_CERT
+    description: "TLS cert path for HTTPS (optional)"
+    prompt: "HTTPS cert"
     password: false
-  - name: IRIS_WS_KEY
-    description: "TLS key path for WSS (optional)"
-    prompt: "WSS key"
+  - name: IRIS_HTTP_KEY
+    description: "TLS key path for HTTPS (optional)"
+    prompt: "HTTPS key"
     password: false