feat: return workspace skill directory from read_skill (#26713)

Workspace skills live on the workspace filesystem, and the agent's read_file
and execute tools already operate there. read_skill now returns "dir", the
absolute skill directory, for workspace skills, so the agent can read or run
bundled supporting files (for example a scripts/ helper) with the workspace
tools. The field is omitted for personal skills, which are database-backed and
have no files. read_skill_file is unchanged.

Generated with Coder Agents on behalf of @kylecarbs.

coderd/x/chatd/chattool/skill.go

@@ -351,8 +351,11 @@ func ReadSkill(options ReadSkillOptions) fantasy.AgentTool {
 				if ok {
 					return response, nil
 				}
+				// Include the absolute skill directory so the agent can
+				// reach supporting files with read_file and execute.
 				return toolResponse(map[string]any{
 					"name":  args.Name,
+					"dir":   content.Dir,
 					"body":  content.Body,
 					"files": nonNilFiles(content.Files),
 				}), nil