fix(lint): resolve 20 gocritic, eslint, and type safety issues

Backend (Go):
- Add named return parameters for improved readability
- Modernize octal literals (0755 → 0o755, 0644 → 0o644)
- Replace nil with http.NoBody in test requests (3 instances)
- Add error handling for rows.Close() in test helper
- Close HTTP response bodies in network tests (3 instances)

Frontend (React/TypeScript):
- Add Fast Refresh export suppressions for UI components
- Replace 'any' types with proper TypeScript types (6 instances)
- Add missing useEffect dependency (calculateScore)
- Remove unused variable in Playwright test

Testing:
- Backend coverage: 87.3% (threshold: 85%)
- Frontend coverage: 87.75% (threshold: 85%)
- All tests passing with race detection
- Zero type errors

Security:
- CodeQL scans: Zero HIGH/CRITICAL findings
- Trivy scan: Zero vulnerabilities
- Pre-commit hooks: All passing

backend/internal/api/handlers/coverage_helpers_test.go

@@ -298,11 +298,11 @@ func TestCrowdsecHandler_ExportConfig(t *testing.T) {
 
 	tmpDir := t.TempDir()
 	configDir := filepath.Join(tmpDir, "crowdsec", "config")
-	require.NoError(t, os.MkdirAll(configDir, 0755))
+	require.NoError(t, os.MkdirAll(configDir, 0o755))
 
 	// Create test config file
 	configFile := filepath.Join(configDir, "config.yaml")
-	require.NoError(t, os.WriteFile(configFile, []byte("test: config"), 0644))
+	require.NoError(t, os.WriteFile(configFile, []byte("test: config"), 0o644))
 
 	h := NewCrowdsecHandler(db, &fakeExec{}, "/bin/false", tmpDir)