feat(mcp-docugen): Task 4-6 template_store, llm_client, generation_store

- TemplateStore: CRUD filesystem + asset dir, frontmatter YAML roundtrip,
  path traversal rejection
- OpenRouterClient: async httpx con retry backoff esponenziale (5xx, 429,
  timeout), no-retry su 4xx, parse usage/cost
- GenerationStore: SQLite aiosqlite con schema generations + ephemeral_assets,
  cleanup TTL, stats aggregate

Root pyproject aggiornato con respx + pytest-cov dev deps.
19 + 11 + 9 + 6 = 45 test totali, tutti passed.

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

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

@@ -0,0 +1,109 @@
+import base64
+
+import pytest
+
+from mcp_docugen.models import TemplateFrontmatter
+from mcp_docugen.template_store import (
+    InvalidFrontmatter,
+    TemplateAlreadyExists,
+    TemplateNotFound,
+    TemplateStore,
+)
+
+
+@pytest.fixture
+def store(tmp_path):
+    return TemplateStore(base_dir=tmp_path)
+
+
+def _fm(name="fattura"):
+    return TemplateFrontmatter(
+        name=name,
+        description="Fattura commerciale",
+        required_variables=[{"name": "cliente", "type": "string"}],
+    )
+
+
+async def test_create_and_get(store):
+    fm = _fm()
+    await store.create(name="fattura", frontmatter=fm, body="# Body {{cliente}}")
+    got = await store.get("fattura")
+    assert got.frontmatter.name == "fattura"
+    assert "# Body {{cliente}}" in got.body
+
+
+async def test_create_duplicate_raises(store):
+    fm = _fm()
+    await store.create(name="fattura", frontmatter=fm, body="body")
+    with pytest.raises(TemplateAlreadyExists):
+        await store.create(name="fattura", frontmatter=fm, body="body")
+
+
+async def test_get_missing_raises(store):
+    with pytest.raises(TemplateNotFound):
+        await store.get("nope")
+
+
+async def test_list_returns_summaries(store):
+    await store.create(name="a", frontmatter=_fm("a"), body="b")
+    await store.create(name="b", frontmatter=_fm("b"), body="b")
+    result = await store.list()
+    names = sorted(t.name for t in result)
+    assert names == ["a", "b"]
+
+
+async def test_update_overwrites(store):
+    await store.create(name="f", frontmatter=_fm("f"), body="old")
+    new_fm = TemplateFrontmatter(name="f", description="new description")
+    await store.update(name="f", frontmatter=new_fm, body="new body")
+    got = await store.get("f")
+    assert got.body == "new body"
+    assert got.frontmatter.description == "new description"
+
+
+async def test_update_missing_raises(store):
+    with pytest.raises(TemplateNotFound):
+        await store.update(name="nope", frontmatter=_fm("nope"), body="x")
+
+
+async def test_delete_removes(store):
+    await store.create(name="f", frontmatter=_fm("f"), body="b")
+    await store.delete("f")
+    with pytest.raises(TemplateNotFound):
+        await store.get("f")
+
+
+async def test_delete_missing_raises(store):
+    with pytest.raises(TemplateNotFound):
+        await store.delete("nope")
+
+
+async def test_assets_are_saved_and_listed(store):
+    png_bytes = b"\x89PNG\r\n\x1a\n"
+    assets = [
+        {
+            "filename": "logo.png",
+            "data_b64": base64.b64encode(png_bytes).decode(),
+            "mime": "image/png",
+        }
+    ]
+    await store.create(name="f", frontmatter=_fm("f"), body="b", assets=assets)
+    got = await store.get("f")
+    asset_names = [a.filename for a in got.assets]
+    assert "logo.png" in asset_names
+    content = await store.read_asset("f", "logo.png")
+    assert content == png_bytes
+
+
+async def test_asset_filename_rejects_path_traversal(store):
+    assets = [{"filename": "../evil.png", "data_b64": "aGk=", "mime": "image/png"}]
+    with pytest.raises(ValueError):
+        await store.create(name="f", frontmatter=_fm("f"), body="b", assets=assets)
+
+
+async def test_frontmatter_parsing_rejects_malformed_yaml(store, tmp_path):
+    template_dir = tmp_path / "broken"
+    template_dir.mkdir()
+    (template_dir / "template.md").write_text("---\nname: :::broken\n---\nbody")
+    with pytest.raises(InvalidFrontmatter):
+        await store.get("broken")