feat(discord): register /approve and /deny as native Discord slash commands

[ygd58]

Fixes #3614

Problem

/approve and /deny were missing from Discord's native slash command registry. In multi-bot servers, Discord routes slash interactions to whichever bot has the command registered — without registration, another bot wins and Hermes never sees the approval.

Fix

Added /approve and /deny slash command handlers using the existing _run_simple_slash helper, consistent with all other Hermes Discord slash commands.

[teknium1]

Thanks for the contribution @ygd58! This fix was independently implemented and merged in PR #4800 (commit aecbf7fa4) about a week after your PR was opened.

Evidence:

• /approve and /deny Discord slash commands are registered at gateway/platforms/discord.py lines 2283–2291 using the same _run_simple_slash pattern you used here.
• Commit aecbf7fa4 (merged as PR fix(discord): register /approve and /deny slash commands, wire up button-based approval UI #4800 on 2026-04-03) explicitly covers the same issue: "Register /approve and /deny as native Discord slash commands so they appear in Discord's command picker."

Closing as already implemented. This is an automated hermes-sweeper review.

[alt-glitch]

Superseded by #4800 — merged PR with /approve /deny slash commands and button-based approval UI.