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/QUIT.json

@@ -2,20 +2,20 @@
   "$schema": "https://json-schema.org/draft/2020-12/schema",
   "$id": "https://sneak.berlin/go/neoirc/schema/commands/QUIT.json",
   "title": "QUIT",
-  "description": "User disconnected. S2C only. RFC 1459 §4.1.6.",
+  "description": "A user left the server. A client sends it to end its session. The server sends it to the users who shared a channel with the user who left. RFC 1459 §4.1.6.",
   "$ref": "../message.json",
   "properties": {
     "command": { "const": "QUIT" },
-    "from": { "type": "string", "description": "Nick that quit." },
+    "from": { "type": "string", "description": "The nick that quit. The server sets it." },
     "body": {
       "type": "array",
       "items": { "type": "string" },
-      "description": "Optional quit reason.",
-      "maxItems": 1
+      "description": "The reason for leaving. A client may send one as the first string, and the server uses 'Client quit' when it does not. The server always sends one string."
     }
   },
-  "required": ["command", "from"],
+  "required": ["command"],
   "examples": [
-    { "command": "QUIT", "from": "alice", "body": ["Connection reset"] }
+    { "command": "QUIT", "body": ["Gone for the day"] },
+    { "command": "QUIT", "from": "alice", "body": ["Connection closed"] }
   ]
 }