fix: security hardening + performance refactoring (code review batch 1)

- IDOR fix: deliberation vote now verifies juryMemberId === ctx.user.id
- Rate limiting: tRPC middleware (100/min), AI endpoints (5/hr), auth IP-based (10/15min)
- 6 compound indexes added to Prisma schema
- N+1 eliminated in processRoundClose (batch updateMany/createMany)
- N+1 eliminated in batchCheckRequirementsAndTransition (3 batch queries)
- Service extraction: juror-reassignment.ts (578 lines)
- Dead code removed: award.ts, cohort.ts, decision.ts (680 lines)
- 35 bare catch blocks replaced across 16 files
- Fire-and-forget async calls fixed
- Notification false positive bug fixed

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

src/server/routers/analytics.ts

@@ -2259,7 +2259,7 @@ export const analyticsRouter = router({
           const config = validateRoundConfig('LIVE_FINAL', round.configJson) as LiveFinalConfig
           observerScoreVisibility = config.observerScoreVisibility ?? 'after_completion'
         }
-      } catch { /* use default */ }
+      } catch (err) { console.error('Failed to parse LIVE_FINAL round config for observer score visibility:', err) /* use default */ }
 
       const session = await ctx.prisma.liveVotingSession.findUnique({
         where: { roundId: input.roundId },