feat(canary): register docx generator in registry

Phase 4 Task 4.5 — adds token.TypeDocx: docx.New() to registry.Build.

Test updates:
- TestBuild_RegistersDocx: new, mirrors the webbug + slowredirect
  registration tests
- TestBuild_PendingTypesNotYetRegistered: drops TypeDocx from the
  pending list (4 remain: pdf, kubeconfig, envfile, mysql)
- TestBuild_OnlyExpectedTypesPresentInPhase3 →
  TestBuild_OnlyExpectedTypesPresentInPhase4: cardinality assertion
  bumped from 2 to 3

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

@@ -6,6 +6,7 @@ package registry
 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/slowredirect"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/webbug"
 )
@@ -20,5 +21,6 @@ func Build(_ Config) Registry {
 	return Registry{
 		token.TypeWebbug:       webbug.New(),
 		token.TypeSlowRedirect: slowredirect.New(),
+		token.TypeDocx:         docx.New(),
 	}
 }

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

@@ -30,6 +30,14 @@ func TestBuild_RegistersSlowRedirect(t *testing.T) {
 	require.Equal(t, token.TypeSlowRedirect, g.Type())
 }
 
+func TestBuild_RegistersDocx(t *testing.T) {
+	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
+	g, ok := reg[token.TypeDocx]
+	require.True(t, ok, "expected docx generator registered")
+	require.NotNil(t, g)
+	require.Equal(t, token.TypeDocx, g.Type())
+}
+
 func TestBuild_UnknownTypeReturnsZeroValue(t *testing.T) {
 	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
 	g, ok := reg["nonexistent-type"]
@@ -40,7 +48,6 @@ func TestBuild_UnknownTypeReturnsZeroValue(t *testing.T) {
 func TestBuild_PendingTypesNotYetRegistered(t *testing.T) {
 	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
 	pending := []token.Type{
-		token.TypeDocx,
 		token.TypePDF,
 		token.TypeKubeconfig,
 		token.TypeEnvfile,
@@ -57,12 +64,12 @@ func TestBuild_PendingTypesNotYetRegistered(t *testing.T) {
 	}
 }
 
-func TestBuild_OnlyExpectedTypesPresentInPhase3(t *testing.T) {
+func TestBuild_OnlyExpectedTypesPresentInPhase4(t *testing.T) {
 	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
 	require.Len(
 		t,
 		reg,
-		2,
+		3,
-		"Phase 3 registers exactly two generators (webbug, slowredirect); other phases append",
+		"Phase 4 registers exactly three generators (webbug, slowredirect, docx); other phases append",
 	)
 }