feat(canary): register pdf generator in registry

Fourth entry in the registry map. Cardinality bumps 3 → 4; pending list
shrinks to {kubeconfig, envfile, mysql} (3 remaining).

  - registry.go: adds the import + token.TypePDF: pdf.New() entry
  - registry_test.go:
      - TestBuild_RegistersPDF added (mirrors RegistersDocx)
      - TypePDF removed from TestBuild_PendingTypesNotYetRegistered
      - TestBuild_OnlyExpectedTypesPresentInPhase4 renamed → InPhase5,
        cardinality assertion bumped 3 → 4

Pre-audit gate clean at HEAD: go build ./... + go vet ./... + go test
-race -timeout=60s ./... + go test -tags=integration -race -timeout=300s
./internal/token/... ./internal/event/... + golangci-lint run ./... all
pass with 0 issues.

PROJECTS/beginner/canary-token-generator/backend/internal/token/generators/registry/registry.go

@@ -7,6 +7,7 @@ import (
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/docx"
+	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/pdf"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/slowredirect"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/webbug"
 )
@@ -22,5 +23,6 @@ func Build(_ Config) Registry {
 		token.TypeWebbug:       webbug.New(),
 		token.TypeSlowRedirect: slowredirect.New(),
 		token.TypeDocx:         docx.New(),
+		token.TypePDF:          pdf.New(),
 	}
 }

PROJECTS/beginner/canary-token-generator/backend/internal/token/generators/registry/registry_test.go

@@ -38,6 +38,14 @@ func TestBuild_RegistersDocx(t *testing.T) {
 	require.Equal(t, token.TypeDocx, g.Type())
 }
 
+func TestBuild_RegistersPDF(t *testing.T) {
+	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
+	g, ok := reg[token.TypePDF]
+	require.True(t, ok, "expected pdf generator registered")
+	require.NotNil(t, g)
+	require.Equal(t, token.TypePDF, g.Type())
+}
+
 func TestBuild_UnknownTypeReturnsZeroValue(t *testing.T) {
 	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
 	g, ok := reg["nonexistent-type"]
@@ -48,7 +56,6 @@ func TestBuild_UnknownTypeReturnsZeroValue(t *testing.T) {
 func TestBuild_PendingTypesNotYetRegistered(t *testing.T) {
 	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
 	pending := []token.Type{
-		token.TypePDF,
 		token.TypeKubeconfig,
 		token.TypeEnvfile,
 		token.TypeMySQL,
@@ -64,12 +71,12 @@ func TestBuild_PendingTypesNotYetRegistered(t *testing.T) {
 	}
 }
 
-func TestBuild_OnlyExpectedTypesPresentInPhase4(t *testing.T) {
+func TestBuild_OnlyExpectedTypesPresentInPhase5(t *testing.T) {
 	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
 	require.Len(
 		t,
 		reg,
-		3,
+		4,
-		"Phase 4 registers exactly three generators (webbug, slowredirect, docx); other phases append",
+		"Phase 5 registers exactly four generators (webbug, slowredirect, docx, pdf); other phases append",
 	)
 }