ci: add comprehensive CI/CD pipeline with 100% coverage enforcement

Created complete CI/CD infrastructure for V2 development:

GitHub Actions Pipeline (.github/workflows/v2-ci.yml):
- Pre-flight checks (branch naming, commit messages)
- Build & dependency validation
- Code quality with 40+ linters (golangci-lint)
- Unit tests with MANDATORY 100% coverage enforcement
- Integration tests with timeout management
- Performance benchmarks (parser < 5ms, detection < 10ms, e2e < 50ms)
- Decimal precision validation
- Modularity validation (component independence)
- Final validation summary with PR comments

Code Quality (.golangci.yml):
- 40+ enabled linters for comprehensive checks
- Cyclomatic complexity limits (max 15)
- Magic number detection
- Security scanning (gosec)
- Style checking with MEV/DEX terminology
- Test file exclusions for appropriate linters

Build Automation (Makefile):
- build, test, test-coverage with 100% enforcement
- lint, fmt, vet, security targets
- deps-download, deps-verify, deps-tidy, deps-check
- validate (full CI/CD locally)
- bench (performance benchmarks)
- check-modularity, check-circular
- Color-coded output for better UX

Git Optimization (.gitattributes):
- LF normalization for cross-platform consistency
- Binary file handling
- Diff settings for Go files
- Merge strategies
- Export-ignore for archives

Git Hooks (.git-hooks/):
- pre-commit: format, tests, vet, secret detection, go.mod tidy
- commit-msg: message format validation
- README with installation instructions
- install-git-hooks.sh script for easy setup

Documentation (docs/planning/05_CI_CD_SETUP.md):
- Complete pipeline architecture diagram
- Local development workflow
- GitHub Actions job descriptions
- Performance optimizations (caching, parallel execution)
- Failure handling and debugging
- Branch protection rules
- Deployment process
- Best practices and troubleshooting

Performance Targets:
- Pipeline duration: < 15 minutes
- Test coverage: 100% (enforced, non-negotiable)
- Parser latency: < 5ms
- Arbitrage detection: < 10ms
- End-to-end: < 50ms

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

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

.git-hooks/commit-msg

@@ -0,0 +1,90 @@
+#!/bin/bash
+#
+# Commit message hook for MEV Bot V2
+# Validates commit message format
+#
+# Install: ln -sf ../../.git-hooks/commit-msg .git/hooks/commit-msg
+#
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+COMMIT_MSG_FILE=$1
+COMMIT_MSG=$(cat "$COMMIT_MSG_FILE")
+
+# Skip if this is a merge commit
+if git rev-parse -q --verify MERGE_HEAD > /dev/null; then
+    echo -e "${GREEN}ℹ️  Merge commit detected, skipping validation${NC}"
+    exit 0
+fi
+
+# Skip if this is an amend
+if [ -n "$GIT_EDITOR" ]; then
+    echo -e "${GREEN}ℹ️  Amend detected, skipping validation${NC}"
+    exit 0
+fi
+
+echo -e "${GREEN}📝 Validating commit message...${NC}"
+
+# Required format: type(scope): description
+# type: feat, fix, perf, refactor, test, docs, build, ci
+# scope: component name (parsers, cache, validation, etc.)
+
+PATTERN="^(feat|fix|perf|refactor|test|docs|build|ci)\([a-z0-9-]+\): .{10,}"
+
+if ! echo "$COMMIT_MSG" | grep -qE "$PATTERN"; then
+    echo -e "${RED}❌ Invalid commit message format${NC}"
+    echo ""
+    echo -e "${YELLOW}Required format:${NC}"
+    echo -e "  type(scope): brief description"
+    echo ""
+    echo -e "${YELLOW}Valid types:${NC}"
+    echo -e "  feat     - New feature"
+    echo -e "  fix      - Bug fix"
+    echo -e "  perf     - Performance improvement"
+    echo -e "  refactor - Code refactoring"
+    echo -e "  test     - Adding or updating tests"
+    echo -e "  docs     - Documentation updates"
+    echo -e "  build    - Build system changes"
+    echo -e "  ci       - CI/CD changes"
+    echo ""
+    echo -e "${YELLOW}Example:${NC}"
+    echo -e "  feat(parsers): add UniswapV2 parser with event validation"
+    echo ""
+    echo -e "${YELLOW}Your message:${NC}"
+    echo -e "  $COMMIT_MSG"
+    echo ""
+    exit 1
+fi
+
+# Check for minimum description length
+DESCRIPTION=$(echo "$COMMIT_MSG" | head -n1 | sed 's/^[^:]*: //')
+if [ ${#DESCRIPTION} -lt 10 ]; then
+    echo -e "${RED}❌ Commit description too short (minimum 10 characters)${NC}"
+    echo -e "${YELLOW}Your description: $DESCRIPTION (${#DESCRIPTION} chars)${NC}"
+    exit 1
+fi
+
+# Check for maximum line length (72 chars for first line)
+FIRST_LINE=$(echo "$COMMIT_MSG" | head -n1)
+if [ ${#FIRST_LINE} -gt 72 ]; then
+    echo -e "${YELLOW}⚠️  Warning: First line exceeds 72 characters (${#FIRST_LINE} chars)${NC}"
+    echo -e "${YELLOW}   Consider shortening the description${NC}"
+    echo ""
+fi
+
+# Encourage including coverage info for test changes
+if echo "$COMMIT_MSG" | grep -q "^test"; then
+    if ! echo "$COMMIT_MSG" | grep -qi "coverage"; then
+        echo -e "${YELLOW}💡 Tip: Consider including coverage info in test commits${NC}"
+        echo ""
+    fi
+fi
+
+echo -e "${GREEN}✅ Commit message format valid${NC}"
+echo ""
+
+exit 0