Give bots skills: runbooks they load when a job matches

A skill is a runbook: a name, a unique slug, a one-line description of when
it applies, and the markdown body. A run only ever sees the slug and
description (one load_skill tool carries them), and reads the whole body
only when it calls the tool, so a long runbook costs nothing until needed.

Skills are the third extension kind beside MCP servers and custom tools, on
the same botExtensionsSql path, so per-bot, per-workspace and all-bots
grants work the same way, and attachDefaultExtensions hands an every-bot
skill to new bots. load_skill is a reserved tool name, so a custom tool
cannot shadow it, and a built-in wins a clash.

Managed on Settings > Skills; ExtensionRow links each kind to its own page
and a skill never reports a failure, since nothing connects or runs.

src/components/general/extension-add-select.tsx

@@ -1,25 +1,26 @@
 import type { BotExtensionsPayload } from "@/src/types";
 import { extensionOptionValue, parseExtensionOptionValue } from "@/src/utils/extension-option-value";
+import extensionNoun from "@/src/utils/extension-noun";
 import InlineAddSelect from "./inline-add-select";
 
 type Props = {
     id: string;
     addable: BotExtensionsPayload["addable"];
     loading?: boolean;
-    onAdd: (params: { kind: "mcp" | "tool"; id: number }) => void;
+    onAdd: (params: { kind: "mcp" | "tool" | "skill"; id: number }) => void;
 };
 
 /**
- * Picks an MCP server or tool to give a bot.
+ * Picks an MCP server, tool or skill to give a bot.
  */
 export default function ExtensionAddSelect({ id, addable, loading, onAdd }: Props) {
     return (
         <InlineAddSelect
             id={id}
-            noun="tool or MCP server"
+            noun="tool, MCP server or skill"
             options={addable.map((item) => ({
                 value: extensionOptionValue(item),
-                title: `${item.kind == "mcp" ? "MCP" : "Tool"} · ${item.name}`,
+                title: `${extensionNoun({ kind: item.kind })}: ${item.name}`,
             }))}
             loading={loading}
             onAdd={({ value }) => {

src/components/general/extension-icon.tsx

@@ -1,9 +1,12 @@
-import { Plug, Wrench } from "lucide-react";
+import { BookOpen, Plug, Wrench } from "lucide-react";
 import type { BotExtension } from "@/src/types";
 
 /**
- * The icon of an MCP server (a plug) or a tool (a wrench).
+ * The icon of an MCP server (a plug), a tool (a wrench) or a skill (a book).
  */
 export default function extensionIcon({ kind }: { kind: BotExtension["kind"] }) {
-    return kind == "mcp" ? Plug : Wrench;
+    if (kind == "mcp") return Plug;
+    if (kind == "skill") return BookOpen;
+
+    return Wrench;
 }