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

@@ -34,7 +34,7 @@ export interface AggregationRequest {
 /**
  * Pipeline step responsible for building final response DTO
  */
-export class ResultAggregator {
+export class AggregateResults {
     public execute(request: AggregationRequest): AnalyzeProjectResponse {
         const metrics = this.calculateMetrics(
             request.sourceFiles,

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

@@ -16,7 +16,7 @@ export interface FileCollectionResult {
 /**
  * Pipeline step responsible for file collection and basic parsing
  */
-export class FileCollectionStep {
+export class CollectFiles {
     constructor(private readonly fileScanner: IFileScanner) {}
 
     public async execute(request: FileCollectionRequest): Promise<FileCollectionResult> {

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

@@ -50,7 +50,7 @@ export interface DetectionResult {
 /**
  * Pipeline step responsible for running all detectors
  */
-export class DetectionPipeline {
+export class ExecuteDetection {
     constructor(
         private readonly hardcodeDetector: IHardcodeDetector,
         private readonly namingConventionDetector: INamingConventionDetector,

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

@@ -15,7 +15,7 @@ export interface ParsingResult {
 /**
  * Pipeline step responsible for AST parsing and dependency graph construction
  */
-export class ParsingStep {
+export class ParseSourceFiles {
     constructor(private readonly codeParser: ICodeParser) {}
 
     public execute(request: ParsingRequest): ParsingResult {