feat: per-position camera settings, material alias dialog, product delete, media browser links

- Per-render-position focal_length_mm/sensor_width_mm (DB → pipeline → Blender)
- FOV-based camera distance with min clamp fix for wide-angle lenses
- Unmapped materials blocking dialog on "Dispatch Renders" with batch alias creation
- Material check endpoint (GET /orders/{id}/check-materials)
- Batch alias endpoint (POST /materials/batch-aliases)
- Quick-map "No alias" badges on Materials page
- Full product hard-delete with storage cleanup (MinIO + disk files + orphaned CadFile)
- Delete button on ProductDetail page with confirmation
- Clickable product names in Media Browser (links to product page)
- Single-line render dispatch/retry (POST /orders/{id}/lines/{id}/dispatch-render)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/api/routers/materials.py

@@ -174,6 +174,62 @@ async def seed_aliases(
     return {"inserted": inserted, "total": total}
 
 
+class BatchAliasMapping(BaseModel):
+    alias: str
+    material_id: uuid.UUID
+
+
+class BatchAliasCreate(BaseModel):
+    mappings: list[BatchAliasMapping]
+
+
+@router.post("/batch-aliases")
+async def batch_create_aliases(
+    body: BatchAliasCreate,
+    user: User = Depends(require_admin_or_pm),
+    db: AsyncSession = Depends(get_db),
+):
+    """Create multiple material aliases in one request.
+
+    Skips aliases that already exist (case-insensitive). Validates that
+    each material_id exists.
+    """
+    created = 0
+    skipped = 0
+
+    for mapping in body.mappings:
+        alias_str = mapping.alias.strip()
+        if not alias_str:
+            skipped += 1
+            continue
+
+        # Verify material exists
+        mat_result = await db.execute(
+            select(Material).where(Material.id == mapping.material_id)
+        )
+        if not mat_result.scalar_one_or_none():
+            raise HTTPException(
+                status.HTTP_404_NOT_FOUND,
+                detail=f"Material {mapping.material_id} not found",
+            )
+
+        # Check if alias already exists (case-insensitive)
+        existing = await db.execute(
+            select(MaterialAlias).where(
+                func.lower(MaterialAlias.alias) == alias_str.lower()
+            )
+        )
+        if existing.scalar_one_or_none():
+            skipped += 1
+            continue
+
+        db.add(MaterialAlias(material_id=mapping.material_id, alias=alias_str))
+        created += 1
+
+    await db.commit()
+    return {"created": created, "skipped": skipped}
+
+
 @router.delete("/aliases/{alias_id}", status_code=status.HTTP_204_NO_CONTENT)
 async def delete_alias(
     alias_id: uuid.UUID,