feat: paste overflow via FlaskPaste for long replies

Add Bot.long_reply() that sends lines directly when under threshold,
or creates a FlaskPaste paste with preview + link when over. Refactor
abuseipdb, alert history, crtsh, dork, exploitdb, and subdomain
plugins to use long_reply(). Configurable paste_threshold (default: 4).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/alert.py

@@ -2012,6 +2012,7 @@ async def cmd_alert(bot, message):
             return
         loop = asyncio.get_running_loop()
         fp = bot.registry._modules.get("flaskpaste")
+        history_lines = []
         for row_id, backend, title, url, date, found_at, short_id, short_url in reversed(rows):
             ts = found_at[:10]
             title = _truncate(title) if title else "(no title)"
@@ -2033,7 +2034,8 @@ async def cmd_alert(bot, message):
             line = f"[{name}/{backend}/{short_id}] ({date or ts}) {title}"
             if display_url:
                 line += f" -- {display_url}"
-            await bot.reply(message, line)
+            history_lines.append(line)
+        await bot.long_reply(message, history_lines, label="history")
         return
 
     # -- info (any user, channel only) ---------------------------------------