feat(mcp-docugen): Task 1-3 config, models, auth middleware

- Settings con Pydantic Settings, validazione env obbligatori
- Shared models: TemplateVariable/Frontmatter, ImageVariable, TokenUsage, GenerationResult, TemplateSummary, TemplateAsset
- ApiKeyAuthMiddleware Bearer token con exempt paths

19 test, tutti passed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

services/mcp-docugen/tests/unit/test_models.py

@@ -0,0 +1,92 @@
+import pytest
+from pydantic import ValidationError
+
+from mcp_docugen.models import (
+    GenerationResult,
+    ImageVariable,
+    TemplateFrontmatter,
+    TemplateVariable,
+    TokenUsage,
+)
+
+
+def test_template_variable_string():
+    v = TemplateVariable(name="cliente", type="string")
+    assert v.name == "cliente"
+    assert v.type == "string"
+
+
+def test_template_variable_image():
+    v = TemplateVariable(name="foto", type="image")
+    assert v.type == "image"
+
+
+def test_template_variable_rejects_unknown_type():
+    with pytest.raises(ValidationError):
+        TemplateVariable(name="x", type="number")
+
+
+def test_template_variable_rejects_empty_name():
+    with pytest.raises(ValidationError):
+        TemplateVariable(name="", type="string")
+
+
+def test_frontmatter_minimal():
+    fm = TemplateFrontmatter(name="fattura", description="Fattura commerciale")
+    assert fm.name == "fattura"
+    assert fm.required_variables == []
+    assert fm.model is None
+    assert fm.instructions_hint is None
+
+
+def test_frontmatter_with_variables():
+    fm = TemplateFrontmatter(
+        name="fattura",
+        description="...",
+        model="anthropic/claude-sonnet-4",
+        required_variables=[
+            {"name": "cliente", "type": "string"},
+            {"name": "foto", "type": "image"},
+        ],
+        instructions_hint="tono formale",
+    )
+    assert len(fm.required_variables) == 2
+    assert fm.required_variables[1].type == "image"
+
+
+def test_frontmatter_name_slug_rules():
+    with pytest.raises(ValidationError):
+        TemplateFrontmatter(name="Fattura Commerciale", description="x")
+    with pytest.raises(ValidationError):
+        TemplateFrontmatter(name="../escape", description="x")
+    with pytest.raises(ValidationError):
+        TemplateFrontmatter(name="-starts-with-dash", description="x")
+
+
+def test_image_variable():
+    img = ImageVariable(kind="image", data_b64="aGVsbG8=", mime="image/png")
+    assert img.mime == "image/png"
+
+
+def test_image_variable_rejects_unsupported_mime():
+    with pytest.raises(ValidationError):
+        ImageVariable(kind="image", data_b64="aGVsbG8=", mime="image/bmp")
+
+
+def test_image_variable_rejects_wrong_kind():
+    with pytest.raises(ValidationError):
+        ImageVariable(kind="file", data_b64="aGVsbG8=", mime="image/png")
+
+
+def test_generation_result_shape():
+    result = GenerationResult(
+        generation_id="abc-123",
+        markdown="# hello",
+        model="anthropic/claude-sonnet-4",
+        tokens=TokenUsage(input=100, output=200),
+        cost_usd=0.01,
+        ephemeral_assets_urls=[],
+        ephemeral_expires_at=None,
+    )
+    assert result.generation_id == "abc-123"
+    assert result.tokens.input == 100