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/numerics/401.json

@@ -2,45 +2,61 @@
   "$schema": "https://json-schema.org/draft/2020-12/schema",
   "$id": "https://sneak.berlin/go/neoirc/schema/numerics/401.json",
   "title": "401 ERR_NOSUCHNICK",
-  "description": "No such nick/channel. RFC 1459 \u00a76.1.",
+  "description": "No user has that nick. RFC 1459 §6.1.",
   "$ref": "../message.json",
   "properties": {
     "command": {
-      "const": "401"
+      "const": "ERR_NOSUCHNICK"
+    },
+    "code": {
+      "const": 401
+    },
+    "from": {
+      "type": "string",
+      "description": "The server name."
     },
     "to": {
-      "type": "string"
+      "type": "string",
+      "description": "The user's nick."
     },
     "params": {
       "type": "array",
       "items": {
         "type": "string"
       },
-      "description": "[target_nick]."
+      "description": "The nick that was not found.",
+      "minItems": 1,
+      "maxItems": 1
     },
     "body": {
       "type": "array",
       "items": {
         "type": "string"
       },
-      "description": "No such nick/channel",
+      "description": "One string: 'No such nick' in answer to a PRIVMSG or NOTICE, and 'No such nick/channel' in answer to anything else.",
+      "minItems": 1,
       "maxItems": 1
     }
   },
   "required": [
     "command",
+    "code",
+    "from",
     "to",
-    "params"
+    "params",
+    "body"
   ],
   "examples": [
     {
-      "command": "401",
+      "command": "ERR_NOSUCHNICK",
+      "code": 401,
+      "from": "neoirc",
       "to": "alice",
       "params": [
         "bob"
       ],
       "body": [
-        "No such nick/channel"
+        "No such nick"
       ]
     }
   ]