Slack DMs still filtered after setting dm_allowed_users

Howdy! Been playing around with Spacebot, super cool so far! I stumbled into a issue with Slack DMs, that could very well be user error, but thought I should report it.

Environment

Spacebot v0.2.1
Linux (Ubuntu Server, systemd)
Socket Mode (no public endpoint)

Problem

Slack direct messages are not being received by Spacebot despite having dm_allowed_users configured in config.toml. This issue seems to be specific to DMs, as channel messages are working correctly. Logs don't provide any evidence the message is ever received.

Spacebot Config

[messaging.slack]
enabled = true
dm_allowed_users = ["Uxxxx"] # Profile -> kebab -> Copy User ID

[[messaging.slack.instances]]
name = "Tempest"
enabled = true
bot_token = "xoxb-..."

Slack Permissions

The Messages Tab is enabled with "Allow users to send Slash commands and messages from the messages tab" checked.

    "oauth_config": {
        "scopes": {
            "bot": [
                "app_mentions:read",
                "chat:write",
                "chat:write.public",
                "chat:write.customize",
                "reactions:read",
                "reactions:write",
                "channels:read",
                "channels:history",
                "groups:read",
                "groups:history",
                "im:read",
                "im:write",
                "im:history",
                "mpim:history",
                "mpim:read",
                "files:read",
                "files:write",
                "users:read"
            ]
        }
    },
    "settings": {
        "event_subscriptions": {
            "bot_events": [
                "app_mention",
                "message.channels",
                "message.groups",
                "message.im",
                "message.mpim"
            ]
        },
        "interactivity": {
            "is_enabled": true
        },
        "org_deploy_enabled": false,
        "socket_mode_enabled": true,
        "token_rotation_enabled": false
    }

App reinstalled, tested on browser slack and desktop slack.

Please let me know if more details are needed, thank you!

Start by tracing the Slack integration's handling of message.im events and the dm_allowed_users setting in config.toml. Reproduce the reported setup with an allowed user, then verify that direct messages are received while channel messages continue to work; add coverage for the regression if the existing test structure supports it.