fix(events): prevent duplicate slash command and button execution

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Bug and impact

Duplicate interaction execution — After the events-handler regression fix (c430893), slash commands and buttons were handled by two independent interactionCreate listeners that ran in parallel:

1. src/events/validations/* validators (calling command.run() / button.run())
2. src/events/Guild/interactionCreate.js and components.js (also calling run())

Because Discord.js does not await async listeners, both paths executed concurrently before interaction.replied was set. This caused:

• Economy corruption — /beg, /deposit, /withdraw applied balance changes twice
• Duplicate DB writes — e.g. /afk set could create two records
• Double dev /eval — arbitrary code executed twice for authorized developers
• Double button side effects — ticket/setup flows could run DB writes twice

Moderation crash — /ban and /kick dereferenced member.bannable / member.kickable when getMember() returned null (user not in guild), causing an uncaught TypeError.

Root cause

Validators were left as full executors while Guild handlers were restored as separate per-module listeners. Three interactionCreate listeners fired in parallel for every interaction.

Fix

• Consolidate all interactionCreate handlers into one sequential listener in src/handlers/events.js (validators first, then command router, then components)
• Change validators to gate only — remove await *.run() calls; Guild handlers own execution
• Make components.js async and await component handlers
• Add null-member guards to /ban and /kick (matching /timeout)

Validation

• npm test — 40/40 passing
• New regression tests:
  • tests/events-handler-shape.test.js — single consolidated listener + validators don't execute
  • tests/moderation-member-null-guard.test.js — ban/kick null guard ordering