bug: Bot messages blocked by user allowlist even after passing bot gate

[rockexe0000]

Description

When allow_bot_messages = "all" is configured, bot messages correctly pass the bot gate (mode check + trusted_bot_ids), but are then rejected by the user allowlist check at src/discord.rs:474. The user gate does not distinguish between bot and human authors, so bot messages are denied unless the bot's ID is manually added to allowed_users.

This means allow_bot_messages and allowed_users are coupled in a way that contradicts the documented behavior — the bot gate should be sufficient to authorize bot messages.

Steps to Reproduce

1. Configure config.toml with:

   allow_bot_messages = "all"
   trusted_bot_ids = []
   allow_all_users = false
   allowed_users = ["<your_human_user_id>"]

2. Have another bot send a message in an allowed channel
3. Observe that the bot reacts with 🚫 and logs "denied user, ignoring"
4. Add the other bot's ID to allowed_users → it works

Expected Behavior

Bot messages that pass the bot gate (allow_bot_messages + trusted_bot_ids) should not be blocked by the user allowlist. The user gate should only apply to human (non-bot) messages.

Environment

• OpenAB version: latest (main branch, commit e914f70)
• Platform: Discord
• Relevant code: src/discord.rs line 474–479

Screenshots / Logs

tracing::info!(user_id = %msg.author.id, "denied user, ignoring");

Suggested fix — add !msg.author.bot guard at line 474:

if !msg.author.bot
    && !self.allow_all_users
    && !self.allowed_users.contains(&msg.author.id.get())
{
    ...
}

src/slack.rs may need the same fix if it shares this pattern.

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