feat: add /export-session command

Export current session to HTML file with full system prompt included.
Uses pi-coding-agent templates for consistent rendering.

Features:
- Exports session entries + full system prompt + tools
- Saves to workspace by default, or custom path
- Optional --open flag to open in browser
- Reuses pi-mono export-html templates

Usage:
  /export-session           # Export to workspace
  /export-session ~/export  # Export to custom path
  /export-session --open    # Export and open in browser

src/auto-reply/reply/commands-info.ts

@@ -7,6 +7,7 @@ import {
   buildHelpMessage,
 } from "../status.js";
 import { buildContextReply } from "./commands-context-report.js";
+import { buildExportSessionReply } from "./commands-export-session.js";
 import { buildStatusReply } from "./commands-status.js";
 
 export const handleHelpCommand: CommandHandler = async (params, allowTextCommands) => {
@@ -168,6 +169,28 @@ export const handleContextCommand: CommandHandler = async (params, allowTextComm
   return { shouldContinue: false, reply: await buildContextReply(params) };
 };
 
+export const handleExportSessionCommand: CommandHandler = async (params, allowTextCommands) => {
+  if (!allowTextCommands) {
+    return null;
+  }
+  const normalized = params.command.commandBodyNormalized;
+  if (
+    normalized !== "/export-session" &&
+    !normalized.startsWith("/export-session ") &&
+    normalized !== "/export" &&
+    !normalized.startsWith("/export ")
+  ) {
+    return null;
+  }
+  if (!params.command.isAuthorizedSender) {
+    logVerbose(
+      `Ignoring /export-session from unauthorized sender: ${params.command.senderId || "<unknown>"}`,
+    );
+    return { shouldContinue: false };
+  }
+  return { shouldContinue: false, reply: await buildExportSessionReply(params) };
+};
+
 export const handleWhoamiCommand: CommandHandler = async (params, allowTextCommands) => {
   if (!allowTextCommands) {
     return null;