feat(testing): add Anvil fork local testing infrastructure

Complete local testing setup with Anvil fork of Arbitrum mainnet:

Infrastructure:
- Docker Compose orchestration (Anvil, MEV Bot, Prometheus, Grafana)
- Anvil fork configuration with 1-second blocks
- Multi-stage Dockerfile for optimized builds
- Health checks and auto-restart policies

Configuration:
- Comprehensive .env.example with all parameters
- Prometheus metrics collection setup
- Grafana datasource provisioning
- .gitignore to prevent committing secrets

Testing Scripts:
- setup-local-fork.sh: Initialize fork and fund test wallet
- create-test-swap.sh: Generate test swaps for bot detection
- Both scripts include validation and helpful output

Integration Components:
- pkg/sequencer/reader.go: WebSocket reader for pending transactions
  - Worker pool pattern (10 workers)
  - <50ms processing target
  - Front-running capability
  - Auto-reconnection with exponential backoff

- pkg/pools/discovery.go: Pool discovery service
  - UniswapV2-style pools (SushiSwap, Camelot)
  - UniswapV3 pools (multiple fee tiers)
  - Factory contract queries
  - Liquidity filtering

Documentation:
- TESTING.md: Complete testing guide
  - Quick start instructions
  - Testing scenarios
  - Monitoring and debugging
  - Performance benchmarks
  - Troubleshooting guide

This enables safe local testing without deploying to public testnet,
using real Arbitrum mainnet state forked locally with Anvil.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

config/grafana/datasources/prometheus.yml

@@ -0,0 +1,11 @@
+apiVersion: 1
+
+datasources:
+  - name: Prometheus
+    type: prometheus
+    access: proxy
+    url: http://prometheus:9090
+    isDefault: true
+    editable: true
+    jsonData:
+      timeInterval: 15s

config/prometheus.yml

@@ -0,0 +1,16 @@
+global:
+  scrape_interval: 15s
+  scrape_timeout: 10s
+  evaluation_interval: 15s
+
+scrape_configs:
+  - job_name: 'mev-bot'
+    static_configs:
+      - targets: ['mev-bot:9090']
+        labels:
+          instance: 'mev-bot-v2'
+          environment: 'testing'
+
+  - job_name: 'prometheus'
+    static_configs:
+      - targets: ['localhost:9090']