#13652: fix(discord): ensure default bot loads when multiple accounts are con…

…figured. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> Fixed a bug where the default Discord bot account would not load when `channels.discord.token` was configured alongside `channels.discord.accounts`. The code now correctly includes the "default" account ID in the account list when a root-level token exists, ensuring the default bot starts properly in multi-account configurations. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with no risk - The change is a targeted bug fix with clear logic: it ensures the default account is included when a root token is configured. The implementation correctly handles the multi-account configuration scenario and aligns with the token resolution logic in `resolveDiscordToken`. No edge cases or potential issues identified. - No files require special attention <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->