feat: API usage in live dashboard + Discord channel names

- Fetch Claude Code usage via OAuth API (five_hour/seven_day)
- Fetch Codex usage via app-server JSON-RPC (rateLimits/read)
- System resources: CPU%, memory, disk in GB with emoji thresholds
- Show actual Discord channel names (#name) instead of DB-stored names
- Guard against overlapping usage updates (async API calls)

src/channels/discord.ts

@@ -464,6 +464,7 @@ export class DiscordChannel implements Channel {
         const jid = channelIdToJid.get(id);
         if (!jid || !channel) continue;
         result.set(jid, {
+          name: channel.name,
           position: channel.position,
           category: channel.parent?.name || '',
           categoryPosition: channel.parent?.position ?? 999,
@@ -478,6 +479,7 @@ export class DiscordChannel implements Channel {
           if (channel && 'position' in channel) {
             const tc = channel as TextChannel;
             result.set(jid, {
+              name: tc.name,
               position: tc.position,
               category: tc.parent?.name || '',
               categoryPosition: tc.parent?.position ?? 999,