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/dork.py

@@ -67,8 +67,9 @@ async def cmd_dork(bot, message):
     subcmd = parts[1].lower()
 
     if subcmd == "list":
-        lines = [f"  {k:<10} {desc}" for k, (_, desc) in sorted(_DORKS.items())]
-        await bot.reply(message, "Dork categories:\n" + "\n".join(lines))
+        lines = ["Dork categories:"]
+        lines.extend(f"  {k:<10} {desc}" for k, (_, desc) in sorted(_DORKS.items()))
+        await bot.long_reply(message, lines, label="dork categories")
         return
 
     if len(parts) < 3: