refactor: remove !paste command, keep as internal helper

Paste creation is only used internally by the bot for multi-line
output. The create_paste() helper remains importable by other plugins.

plugins/flaskpaste.py

@@ -151,34 +151,6 @@ def create_paste(bot, content: str) -> str | None:
 
 # -- Commands ----------------------------------------------------------------
 
-@command("paste", help="Create a paste: !paste <text>")
-async def cmd_paste(bot, message):
-    """Create a paste on FlaskPaste and return the URL.
-
-    Usage:
-        !paste some long text here
-    """
-    parts = message.text.split(None, 1)
-    if len(parts) < 2:
-        await bot.reply(message, "Usage: !paste <text>")
-        return
-
-    content = parts[1]
-    base_url = _get_base_url(bot)
-    loop = asyncio.get_running_loop()
-
-    try:
-        url = await loop.run_in_executor(None, _create_paste, base_url, content)
-    except Exception as exc:
-        await bot.reply(message, f"paste failed: {exc}")
-        return
-
-    if url:
-        await bot.reply(message, url)
-    else:
-        await bot.reply(message, "paste failed: no URL returned")
-
-
 @command("shorten", help="Shorten a URL: !shorten <url>")
 async def cmd_shorten(bot, message):
     """Shorten a URL via FlaskPaste.