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/TOPIC.json

@@ -2,20 +2,24 @@
   "$schema": "https://json-schema.org/draft/2020-12/schema",
   "$id": "https://sneak.berlin/go/neoirc/schema/commands/TOPIC.json",
   "title": "TOPIC",
-  "description": "Get or set channel topic. C2S: set topic (body present) or query (body absent). S2C: topic change notification. RFC 1459 §4.2.4.",
+  "description": "Set a channel's topic. A client sends it to set the topic. The server sends it to every member of the channel when the topic changes. RFC 1459 §4.2.4.",
   "$ref": "../message.json",
   "properties": {
     "command": { "const": "TOPIC" },
-    "from": { "type": "string", "description": "Nick that changed the topic (S2C)." },
-    "to": { "type": "string", "description": "Channel name.", "pattern": "^#[a-zA-Z0-9_-]+$" },
+    "from": { "type": "string", "description": "The nick that set the topic. The server sets it." },
+    "to": {
+      "type": "string",
+      "description": "The channel name. The server adds the # if a client leaves it out.",
+      "pattern": "^#?[a-zA-Z0-9_-]{1,63}$"
+    },
     "body": {
       "type": "array",
       "items": { "type": "string" },
-      "description": "New topic text (single-element array). Empty array clears the topic.",
-      "maxItems": 1
+      "description": "The new topic. The server joins a client's strings with spaces, and sends the topic as one string. [\"\"] clears the topic.",
+      "minItems": 1
     }
   },
-  "required": ["command", "to"],
+  "required": ["command", "to", "body"],
   "examples": [
     { "command": "TOPIC", "from": "alice", "to": "#general", "body": ["Welcome to the channel"] }
   ]