refactor: structured logging across server

Create server/src/lib/logger.ts with info/warn/error methods that add
[botfights:tag] timestamps. Replace bare console.log/warn/error calls
in index.ts, seed.ts, routes/fights.ts, engine/queue.ts, engine/mock.ts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/engine/queue.ts

@@ -1,4 +1,5 @@
 import { db, schema } from '../db/index.js'
+import { logger } from '../lib/logger.js'
 import { eq } from 'drizzle-orm'
 import { runFightAsync, isInFight } from './orchestrator.js'
 import { seedMockBots } from './mock.js'
@@ -69,7 +70,7 @@ export async function joinQueue(botId: string): Promise<string> {
     throw new Error('Bot is deactivated due to webhook errors. Re-test your webhook to reactivate.')
   }
 
-  console.log(`[queue] joinQueue botId=${botId} name=${bot.name} webhook=${bot.webhookUrl}`)
+  logger.info('queue', `joinQueue botId=${botId} name=${bot.name} webhook=${bot.webhookUrl}`)
 
   // Don't allow same bot twice in queue
   const existing = waitingQueue.findIndex(e => e.botId === botId)
@@ -145,7 +146,7 @@ async function startFight(botAId: string, botBId: string): Promise<string> {
 }
 
 async function matchAgainstMock(botId: string, webhookUrl: string): Promise<string> {
-  console.log(`[queue] matchAgainstMock botId=${botId} webhook=${webhookUrl}`)
+  logger.info('queue', `matchAgainstMock botId=${botId} webhook=${webhookUrl}`)
   const allBots = await db.select({
     id: schema.bots.id,
     webhookUrl: schema.bots.webhookUrl,
@@ -155,7 +156,7 @@ async function matchAgainstMock(botId: string, webhookUrl: string): Promise<stri
   const mockBots = allBots.filter(b => b.id !== botId && b.webhookUrl.startsWith('http://mock.local'))
 
   if (mockBots.length === 0) {
-    console.log('[queue] No mock bots found, seeding...')
+    logger.info('queue', 'No mock bots found, seeding...')
     await seedMockBots()
     return matchAgainstMock(botId, webhookUrl)
   }
@@ -166,6 +167,6 @@ async function matchAgainstMock(botId: string, webhookUrl: string): Promise<stri
   mockBots.sort((a, b) => Math.abs(a.eloRating - botElo) - Math.abs(b.eloRating - botElo))
   const opponent = mockBots[0]
 
-  console.log(`[queue] starting fight: ${botId} vs mock ${opponent.id}`)
+  logger.info('queue', `starting fight: ${botId} vs mock ${opponent.id}`)
   return runFightAsync(botId, opponent.id)
 }