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>

templates/model-entity.spec.mustache

@@ -0,0 +1,34 @@
+{{#models}}
+{{#model}}
+import { {{classname}} } from './{{classFilename}}.model';
+import { mock{{classname}}Model } from './{{classFilename}}.model.mock';
+
+describe('{{classname}}', () => {
+  it('should create an instance', () => {
+    const model = new {{classname}}();
+
+    expect(model).toBeInstanceOf({{classname}});
+  });
+
+{{#vars}}
+  it('should allow setting {{name}}', () => {
+    const model = new {{classname}}();
+    const expected = mock{{classname}}Model();
+    model.{{name}} = expected.{{name}};
+
+    expect(model.{{name}}).toBe(expected.{{name}});
+  });
+
+{{/vars}}
+  it('should build a valid model from mock', () => {
+    const model = mock{{classname}}Model();
+
+    expect(model).toBeInstanceOf({{classname}});
+{{#vars}}
+    expect(model.{{name}}).toBeDefined();
+{{/vars}}
+  });
+});
+
+{{/model}}
+{{/models}}