feat: add .spec.ts generation for models, mappers, repositories and use-cases

Add 4 new Mustache templates for generating unit test specs:
- model-entity.spec.mustache: tests instantiation, property setting, mock builder
- mapper.spec.mustache: tests per-property DTO→Entity mapping, instanceof, all fields
- api.repository.impl.spec.mustache: tests HTTP method, response mapping, error propagation
- api.use-cases.impl.spec.mustache: tests repository delegation, observable forwarding

Generator changes:
- Add uppercaseHttpMethod to TagOperation for spec HTTP assertions
- Add testValue to TagOperationParam for auto-generated test arguments
- Add resolveTestParamValue utility for primitive/complex type test literals
- Add specs counter to GeneratedCount and GenerationReport
- Wire 4 new renderTemplate calls in schema and tag loops
- Update report generator to count .spec.ts files

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/types/generation.types.ts

@@ -8,6 +8,7 @@ export interface GeneratedCount {
   useCases: number;
   providers: number;
   mocks: number;
+  specs: number;
 }
 
 /**
@@ -25,5 +26,6 @@ export interface GenerationReport {
     useCases: number;
     providers: number;
     mocks: number;
+    specs: number;
   };
 }