refactor: extract all hardcoded values to constants (v0.8.1)

Fix all 63 hardcoded value issues from Guardian self-check:
- Remove hardcoded Slack token from documentation
- Remove aws-sdk framework leak from domain layer
- Rename 4 pipeline files to verb-noun convention
- Extract 57 magic strings to SecretExamples.ts constants
- Update SecretViolation, SecretDetector, MagicStringMatcher
- Use typeof for TypeScript literal type in getSeverity()

Result: 0 issues in Guardian self-check (was 63)
All 566 tests passing, build successful

packages/guardian/src/application/use-cases/pipeline/AggregateResults.ts

@@ -0,0 +1,84 @@
+import { SourceFile } from "../../../domain/entities/SourceFile"
+import { DependencyGraph } from "../../../domain/entities/DependencyGraph"
+import type {
+    AggregateBoundaryViolation,
+    AnalyzeProjectResponse,
+    ArchitectureViolation,
+    CircularDependencyViolation,
+    DependencyDirectionViolation,
+    EntityExposureViolation,
+    FrameworkLeakViolation,
+    HardcodeViolation,
+    NamingConventionViolation,
+    ProjectMetrics,
+    RepositoryPatternViolation,
+    SecretViolation,
+} from "../AnalyzeProject"
+
+export interface AggregationRequest {
+    sourceFiles: SourceFile[]
+    dependencyGraph: DependencyGraph
+    totalFunctions: number
+    violations: ArchitectureViolation[]
+    hardcodeViolations: HardcodeViolation[]
+    circularDependencyViolations: CircularDependencyViolation[]
+    namingViolations: NamingConventionViolation[]
+    frameworkLeakViolations: FrameworkLeakViolation[]
+    entityExposureViolations: EntityExposureViolation[]
+    dependencyDirectionViolations: DependencyDirectionViolation[]
+    repositoryPatternViolations: RepositoryPatternViolation[]
+    aggregateBoundaryViolations: AggregateBoundaryViolation[]
+    secretViolations: SecretViolation[]
+}
+
+/**
+ * Pipeline step responsible for building final response DTO
+ */
+export class AggregateResults {
+    public execute(request: AggregationRequest): AnalyzeProjectResponse {
+        const metrics = this.calculateMetrics(
+            request.sourceFiles,
+            request.totalFunctions,
+            request.dependencyGraph,
+        )
+
+        return {
+            files: request.sourceFiles,
+            dependencyGraph: request.dependencyGraph,
+            violations: request.violations,
+            hardcodeViolations: request.hardcodeViolations,
+            circularDependencyViolations: request.circularDependencyViolations,
+            namingViolations: request.namingViolations,
+            frameworkLeakViolations: request.frameworkLeakViolations,
+            entityExposureViolations: request.entityExposureViolations,
+            dependencyDirectionViolations: request.dependencyDirectionViolations,
+            repositoryPatternViolations: request.repositoryPatternViolations,
+            aggregateBoundaryViolations: request.aggregateBoundaryViolations,
+            secretViolations: request.secretViolations,
+            metrics,
+        }
+    }
+
+    private calculateMetrics(
+        sourceFiles: SourceFile[],
+        totalFunctions: number,
+        _dependencyGraph: DependencyGraph,
+    ): ProjectMetrics {
+        const layerDistribution: Record<string, number> = {}
+        let totalImports = 0
+
+        for (const file of sourceFiles) {
+            if (file.layer) {
+                layerDistribution[file.layer] = (layerDistribution[file.layer] || 0) + 1
+            }
+            totalImports += file.imports.length
+        }
+
+        return {
+            totalFiles: sourceFiles.length,
+            totalFunctions,
+            totalImports,
+            layerDistribution,
+        }
+    }
+}