fix: POST for file creation (Gitea 1.25+), add edit_issue tool, persist poll state

- files.ts: Use POST for new files, PUT for updates (Gitea 1.25 requires this)
- issues.ts: Add editIssue() for state/title/body changes
- write-tools.ts: Add gitea_edit_issue tool (open/close/edit issues)
- webhook/server.ts: Persist lastPollAt to disk to prevent duplicate
  events on reload; use followUp delivery to queue events during LLM turns
- index.ts: Use deliverAs:'followUp' for sendUserMessage

pi-extension/index.ts

@@ -16,7 +16,11 @@ export default function (pi: ExtensionAPI) {
 	pi.on("session_start", async (_event, ctx) => {
 		console.log("[pi-gitea] Session started");
 
-		const sendMessageFn = ctx.sendUserMessage || ((_msg: string) => Promise.resolve());
+		const sendMessageFn = (msg: string) => {
+			// Use followUp so events queue when the LLM is already processing
+			ctx.sendUserMessage(msg, { deliverAs: "followUp" });
+			return Promise.resolve();
+		};
 		setSendMessage(sendMessageFn);
 
 		try {