core: add peer type "agent" (#7738)

* add agent peer type

* bot types

* agent app icons

* refactor

* smaller image

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Co-authored-by: Evgeny @ SimpleX Chat <259188159+evgeny-simplex@users.noreply.github.com>

docs/protocol/simplex-chat.schema.json

@@ -25,7 +25,7 @@
           "metadata": {"comment": "profile bio (160 characters)"}
         },
         "contactLink": {"ref": "connReqUri"},
-        "peerType": {"enum": ["human", "bot"]},
+        "peerType": {"enum": ["human", "bot", "agent"]},
         "preferences": {
           "optionalProperties": {
             "commands": {