feat(sproutclaw): modularize webui, extensions, and agent config layout

Restructure local extensions into per-feature directories, split WebUI
into backend modules with slash commands and systemd support, and track
prompts/skills under .pi/agent for portable Gitea deployment.

Co-authored-by: Cursor <cursoragent@cursor.com>

.pi/agent/extensions/webui/backend/services/slash-commands.ts

@@ -0,0 +1,51 @@
+import { BUILTIN_SLASH_COMMANDS } from "../../../../../../packages/coding-agent/src/core/slash-commands.ts";
+import { filterWebUiSlashCommands, type SlashCommandEntry } from "../slash/dispatch.ts";
+import type { SendCmd } from "../types/context.ts";
+
+export async function listSlashCommands(sendCmd: SendCmd): Promise<SlashCommandEntry[]> {
+	const builtinNames = new Set(BUILTIN_SLASH_COMMANDS.map((command) => command.name));
+	const commands: SlashCommandEntry[] = BUILTIN_SLASH_COMMANDS.map((command) => ({
+		name: command.name,
+		description: command.description,
+		source: "builtin",
+	}));
+
+	const response = await sendCmd({ type: "get_commands" });
+	if (!response.success) throw new Error(response.error || "读取命令失败");
+
+	for (const command of response.data?.commands || []) {
+		const name = String(command?.name || "");
+		if (!name) continue;
+
+		const source = String(command?.source || "");
+		if (source === "extension" && builtinNames.has(name)) continue;
+
+		if (source === "prompt") {
+			commands.push({
+				name,
+				description: String(command.description || ""),
+				source: "prompt",
+			});
+			continue;
+		}
+
+		if (source === "skill") {
+			commands.push({
+				name,
+				description: String(command.description || ""),
+				source: "skill",
+			});
+			continue;
+		}
+
+		if (source === "extension") {
+			commands.push({
+				name,
+				description: String(command.description || ""),
+				source: "extension",
+			});
+		}
+	}
+
+	return filterWebUiSlashCommands(commands).sort((a, b) => a.name.localeCompare(b.name));
+}