`CommandTree.allowed_contexts` not properly overridden by `@app_commands.dm_only()`, et al.

[Kenny2github]

Summary

The @app_commands.dm_only() decorator and its kin do not actually override CommandTree.{allowed_contexts,allowed_installs}

Reproduction Steps

1. Set all three flags on CommandTree.allowed_contexts
2. Add a @dm_only() command
3. The command's final allowed contexts are those of the CommandTree, not the command, contrary to the documentation of the former ("Note that you can override this on a per command basis.")

Minimal Reproducible Code

from discord import Intents
from discord.ext.commands import Bot
from discord.app_commands import AppCommandContext, dm_only

bot = Bot(
    command_prefix='/',
    intents=Intents.all(),
    allowed_contexts=AppCommandContext(guild=True, dm_channel=True, private_channel=True)
)

@bot.tree.command()
@dm_only()
async def test(ctx):
    pass

contexts = test.to_dict(bot.tree)['contexts']
print(contexts)
assert contexts == [1]

Expected Results

The @dm_only() command /test should only have context 1 (dm_channel):

[1]

Actual Results

The command has contexts 0 (guild), 1 (dm_channel), and 2 (private_channel):

[0, 1, 2]
Traceback (most recent call last):
  File "<string>", line 18, in <module>
    assert contexts == [1]
           ^^^^^^^^^^^^^^^
AssertionError

Intents

discord.Intents.all()

System Information

• Python v3.13.0-final
• discord.py v2.5.2-final
• aiohttp v3.11.18
• system info: Windows 11 10.0.26100

Checklist

• [x] I have searched the open issues for duplicates.
• [x] I have shown the entire traceback, if possible.
• [x] I have removed my token from display, if visible.

Additional Context

Since they are implemented with similarly flawed logic, similar issues may also apply to the following classes, decorators, and/or attributes:

• @app_commands.guild_only()
• @app_commands.private_channel_only()
• @app_commands.user_install()
• @app_commands.guild_install()
• app_commands.AppInstallationType
• CommandTree.allowed_installs