Migrate status updates from Discord to Root mail system

[Copilot]

Replaces Discord channel-based status update tracking with Root's mail query system. This removes 200+ lines of Discord-specific mutation code in favor of direct Root API queries.

Core Changes

• Status updates: Query Root directly for daily reports instead of tracking via Discord messages and reactions
• GraphQL refactor: Split mutations into separate module, converted queries/mutations to client methods, introduced shared reqwest client
• Tracing infrastructure: New trace.rs module with dynamic log level control and span instrumentation across main, scheduler, tasks, and commands
• Config extraction: Bot configuration moved to dedicated config.rs with BotConfig struct

Breaking Changes

• Status update system requires Root integration (no Discord channel fallback)
• Environment variable OWNER_ID type changed

Technical Debt

• Status update migration is MVP-grade, needs cleanup
• Fourth-year tracking removed (business logic change)

// Before: Discord mutation-heavy approach
send_status_update_mutation(&channel_id, &user_data).await?;

// After: Direct Root query
let report = client.get_status_update_report(date).await?;

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