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/status-line/index.ts

@@ -0,0 +1,40 @@
+/**
+ * Status Line Extension
+ *
+ * Demonstrates ctx.ui.setStatus() for displaying persistent status text in the footer.
+ * Shows turn progress with themed colors.
+ */
+
+import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+
+export default function (pi: ExtensionAPI) {
+	let turnCount = 0;
+
+	pi.on("session_start", async (_event, ctx) => {
+		const theme = ctx.ui.theme;
+		ctx.ui.setStatus("status-demo", theme.fg("dim", "Ready"));
+	});
+
+	pi.on("turn_start", async (_event, ctx) => {
+		turnCount++;
+		const theme = ctx.ui.theme;
+		const spinner = theme.fg("accent", "●");
+		const text = theme.fg("dim", ` Turn ${turnCount}...`);
+		ctx.ui.setStatus("status-demo", spinner + text);
+	});
+
+	pi.on("turn_end", async (_event, ctx) => {
+		const theme = ctx.ui.theme;
+		const check = theme.fg("success", "✓");
+		const text = theme.fg("dim", ` Turn ${turnCount} complete`);
+		ctx.ui.setStatus("status-demo", check + text);
+	});
+
+	pi.on("session_switch", async (event, ctx) => {
+		if (event.reason === "new") {
+			turnCount = 0;
+			const theme = ctx.ui.theme;
+			ctx.ui.setStatus("status-demo", theme.fg("dim", "Ready"));
+		}
+	});
+}