Make the schema files match the server (closes #218)

Each file in schema/ now describes what the HTTP API on next sends and
accepts. A numeric reply has its name in command and its number in code.
body is always an array of strings. MODE, KICK and JOIN carry their
values in body, and TOPIC needs a non-empty body. PING takes no token,
and its PONG is the HTTP response. A channel name is limited to 63
characters, and the leading # is optional from a client.

PUBKEY.json is deleted, since the server has no such command. The
section of schema/README.md that listed the differences is removed,
and the sentences it made false are corrected.

Model: opus-5-5

schema/commands/JOIN.json

@@ -2,15 +2,25 @@
   "$schema": "https://json-schema.org/draft/2020-12/schema",
   "$id": "https://sneak.berlin/go/neoirc/schema/commands/JOIN.json",
   "title": "JOIN",
-  "description": "Join a channel. C2S: request to join. S2C: notification that a user joined. RFC 1459 §4.2.1.",
+  "description": "Join a channel. A client sends it to join a channel, which the server creates if it does not exist. The server sends it to every member of the channel when a user joins, the new member included. RFC 1459 §4.2.1.",
   "$ref": "../message.json",
   "properties": {
     "command": { "const": "JOIN" },
-    "from": { "type": "string", "description": "Nick that joined (S2C)." },
-    "to": { "type": "string", "description": "Channel name.", "pattern": "^#[a-zA-Z0-9_-]+$" }
+    "from": { "type": "string", "description": "The nick that joined. The server sets it." },
+    "to": {
+      "type": "string",
+      "description": "The channel name: # and then 1 to 63 of a-z, A-Z, 0-9, _ and -. The server adds the # if a client leaves it out.",
+      "pattern": "^#?[a-zA-Z0-9_-]{1,63}$"
+    },
+    "body": {
+      "type": "array",
+      "items": { "type": "string" },
+      "description": "From a client: the channel key as the first string, which a channel with mode +k needs. From the server: the channel name. After a login, and for GET /api/v1/state?initChannelState=1, the server queues a JOIN for each of the session's channels. That JOIN has an empty body."
+    }
   },
   "required": ["command", "to"],
   "examples": [
-    { "command": "JOIN", "from": "alice", "to": "#general" }
+    { "command": "JOIN", "to": "#general" },
+    { "command": "JOIN", "from": "alice", "to": "#general", "body": ["#general"] }
   ]
 }