feat: consolidated Gitea API client and pi extension

- Pure fetch-based API client (src/) with zero external dependencies
- Pi extension adapter (pi-extension/) registering 17 tools
- Standalone CLI (cli.ts) replacing gitea-scripts/gitea.js
- Token auth everywhere (no HMAC secrets)
- SKILL.md for agent auto-discovery
- TOOL.md with full parameter reference

Consolidates pi-bot/extensions/pi-gitea and clawbot/gitea-scripts
into a single shared package.

pi-extension/index.ts

@@ -0,0 +1,35 @@
+/**
+ * pi-gitea Extension — entry point
+ *
+ * Registers Gitea tools (read + write) and optional webhook server.
+ */
+
+import registerReadTools from "./tools/read-tools.js";
+import registerWriteTools from "./tools/write-tools.js";
+import { startWebhookServer, stopWebhookServer, startPolling, stopPolling, setSendMessage } from "./webhook/server.js";
+import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+
+export default function (pi: ExtensionAPI) {
+	registerReadTools(pi);
+	registerWriteTools(pi);
+
+	pi.on("session_start", async (_event, ctx) => {
+		console.log("[pi-gitea] Session started");
+
+		const sendMessageFn = ctx.sendUserMessage || ((_msg: string) => Promise.resolve());
+		setSendMessage(sendMessageFn);
+
+		try {
+			await startWebhookServer(pi);
+			startPolling(pi);
+		} catch (err) {
+			console.error("[pi-gitea] Failed to start webhook server:", err);
+		}
+	});
+
+	pi.on("session_shutdown", async () => {
+		console.log("[pi-gitea] Session shutting down");
+		await stopWebhookServer();
+		stopPolling();
+	});
+}