feat: add chat send contract

contracts/v1/chat-send-request.json

@@ -0,0 +1,13 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://trixie.reaperofveriod.nl/contracts/v1/chat-send-request.json",
+  "title": "Twitch chat send request",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["identity", "message"],
+  "properties": {
+    "identity": { "enum": ["streamer", "bot"] },
+    "message": { "type": "string", "minLength": 1, "maxLength": 500 },
+    "reply_parent_message_id": { "type": "string", "maxLength": 128 }
+  }
+}

contracts/v1/chat-send-response.json

@@ -0,0 +1,13 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://trixie.reaperofveriod.nl/contracts/v1/chat-send-response.json",
+  "title": "Twitch chat send response",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["message_id", "is_sent"],
+  "properties": {
+    "message_id": { "type": "string", "minLength": 1 },
+    "is_sent": { "type": "boolean" },
+    "drop_reason": { "type": ["string", "null"] }
+  }
+}

fixtures/v1/chat-send.response.json

@@ -0,0 +1,5 @@
+{
+  "message_id": "synthetic-message-id",
+  "is_sent": true,
+  "drop_reason": null
+}