feat: FASE 6.5 - Report PDF (WeasyPrint + Kaleido)

Add PDF report generation for Metrologist dashboard with SPC and
measurement reports including SVG charts, capability indices, and
company logo embedding.

New files:
- server/services/report_service.py (Jinja2 + Plotly/Kaleido + WeasyPrint)
- server/routers/reports.py (2 GET endpoints with auth)
- server/templates/reports/ (base, spc, measurement HTML templates)

Modified:
- server/main.py (register reports router)
- client dashboard (download buttons + proxy routes)
- i18n strings IT/EN

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/routers/reports.py

@@ -0,0 +1,81 @@
+"""Reports router — PDF report generation endpoints for Metrologist."""
+from datetime import datetime
+
+from fastapi import APIRouter, Depends, HTTPException, Query, status
+from fastapi.responses import Response
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from database import get_db
+from middleware.api_key import require_metrologist
+from models.user import User
+from services.report_service import generate_measurement_report, generate_spc_report
+
+router = APIRouter(prefix="/api/reports", tags=["reports"])
+
+
+@router.get("/spc")
+async def download_spc_report(
+    recipe_id: int = Query(...),
+    subtask_id: int = Query(...),
+    version_id: int | None = Query(None),
+    date_from: datetime | None = Query(None),
+    date_to: datetime | None = Query(None),
+    operator_id: int | None = Query(None),
+    lot_number: str | None = Query(None),
+    serial_number: str | None = Query(None),
+    user: User = Depends(require_metrologist),
+    db: AsyncSession = Depends(get_db),
+) -> Response:
+    """Generate and download SPC PDF report."""
+    try:
+        pdf_bytes = await generate_spc_report(
+            db, recipe_id, subtask_id,
+            version_id, date_from, date_to,
+            operator_id, lot_number, serial_number,
+        )
+    except Exception as e:
+        raise HTTPException(
+            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+            detail=f"Report generation failed: {str(e)}",
+        )
+
+    filename = f"spc_report_recipe{recipe_id}_st{subtask_id}.pdf"
+    return Response(
+        content=pdf_bytes,
+        media_type="application/pdf",
+        headers={"Content-Disposition": f'attachment; filename="{filename}"'},
+    )
+
+
+@router.get("/measurements")
+async def download_measurement_report(
+    recipe_id: int = Query(...),
+    subtask_id: int | None = Query(None),
+    version_id: int | None = Query(None),
+    date_from: datetime | None = Query(None),
+    date_to: datetime | None = Query(None),
+    operator_id: int | None = Query(None),
+    lot_number: str | None = Query(None),
+    serial_number: str | None = Query(None),
+    user: User = Depends(require_metrologist),
+    db: AsyncSession = Depends(get_db),
+) -> Response:
+    """Generate and download measurement table PDF report."""
+    try:
+        pdf_bytes = await generate_measurement_report(
+            db, recipe_id, subtask_id,
+            version_id, date_from, date_to,
+            operator_id, lot_number, serial_number,
+        )
+    except Exception as e:
+        raise HTTPException(
+            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+            detail=f"Report generation failed: {str(e)}",
+        )
+
+    filename = f"measurements_report_recipe{recipe_id}.pdf"
+    return Response(
+        content=pdf_bytes,
+        media_type="application/pdf",
+        headers={"Content-Disposition": f'attachment; filename="{filename}"'},
+    )