feat(discord_bot): hybrid sync command + automatic startup guild sync

[extreme4all]

Summary

• make the sync command a hybrid command (!sync and /sync), owner + guild only
• log sync callers (author, author_id, guild, spec, target guilds) and results as structured logs, matching the cogs' logging style
• log failed per-guild syncs instead of silently swallowing discord.HTTPException
• sync the command tree to SYNC_GUILD_ID in setup_hook on startup (instant, guild-scoped) so deploys no longer rely on manual !sync
• new optional setting SYNC_GUILD_ID; when unset, startup sync is skipped with a warning

Commits

1. refactor(discord_bot): make sync command a hybrid command
2. feat(discord_bot): log sync command callers and results
3. fix(discord_bot): log failed guild syncs instead of swallowing http errors
4. feat(discord_bot): sync command tree to sync_guild on startup

Verification

• Greedy[discord.Object] + Literal spec register correctly as a hybrid app command on discord.py 2.2.2 (smoke-tested HybridAppCommand construction)
• sync_command_tree smoke-tested: skip path warns when SYNC_GUILD_ID unset; guild path copies global commands and syncs to the guild
• ruff check + ruff format --check pass
• 44 discord bot tests pass

Deploy note

Set SYNC_GUILD_ID in the discord_bot deployment env to enable automatic sync. Existing global commands remain; guild commands shadow them. To clean up duplicates later, clear the guild tree once (!sync ^) and do a final global !sync.