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/utils/bot-extensions-sql.test.ts

@@ -8,6 +8,9 @@ beforeAll(() => {
     db.run(`CREATE TABLE custom_tools (id INTEGER PRIMARY KEY, all_bots INTEGER, enabled INTEGER)`);
     db.run(`CREATE TABLE bot_custom_tools (bot_id INTEGER, custom_tool_id INTEGER)`);
     db.run(`CREATE TABLE workspace_custom_tools (workspace_id INTEGER, custom_tool_id INTEGER)`);
+    db.run(`CREATE TABLE skills (id INTEGER PRIMARY KEY, all_bots INTEGER, enabled INTEGER)`);
+    db.run(`CREATE TABLE bot_skills (bot_id INTEGER, skill_id INTEGER)`);
+    db.run(`CREATE TABLE workspace_skills (workspace_id INTEGER, skill_id INTEGER)`);
     /**
      * 1: every bot (given to 5 and 6). 2: bot 5. 3: workspace 9. 4: off,
      * given to 5. 5: nobody. 6: every bot, but 6 dropped it.
@@ -15,6 +18,12 @@ beforeAll(() => {
     db.run(`INSERT INTO custom_tools VALUES (1, 1, 1), (2, 0, 1), (3, 0, 1), (4, 1, 0), (5, 0, 1), (6, 1, 1)`);
     db.run(`INSERT INTO bot_custom_tools VALUES (5, 1), (6, 1), (5, 2), (5, 4), (5, 6)`);
     db.run(`INSERT INTO workspace_custom_tools VALUES (9, 3)`);
+    /**
+     * The same shape, so skills reach a bot the same way.
+     */
+    db.run(`INSERT INTO skills VALUES (1, 1, 1), (2, 0, 1), (3, 0, 1), (4, 1, 0), (5, 0, 1), (6, 1, 1)`);
+    db.run(`INSERT INTO bot_skills VALUES (5, 1), (6, 1), (5, 2), (5, 4), (5, 6)`);
+    db.run(`INSERT INTO workspace_skills VALUES (9, 3)`);
 });
 
 function ids(params: Parameters<typeof botExtensionsSql>[0]) {
@@ -37,4 +46,11 @@ describe("botExtensionsSql", () => {
         expect(ids({ kind: "tool", bot_id: 5, workspace_id: 9 })).toEqual([1, 2, 3, 6]);
         expect(ids({ kind: "tool", bot_id: 5, workspace_id: 8 })).toEqual([1, 2, 6]);
     });
+
+    test("skills reach a bot the same way", () => {
+        expect(ids({ kind: "skill", bot_id: 5 })).toEqual([1, 2, 6]);
+        expect(ids({ kind: "skill", bot_id: 6 })).toEqual([1]);
+        expect(ids({ kind: "skill", bot_id: 7 })).toEqual([]);
+        expect(ids({ kind: "skill", bot_id: 6, workspace_id: 9 })).toEqual([1, 3]);
+    });
 });