feat(phase4+5): role hierarchy, tenant config, fallback material, dead code removal

Phase 4.1 — Role Hierarchy:
  - UserRole enum: add global_admin (platform operator) + tenant_admin
    (per-tenant admin); keep legacy 'admin' for backward compat
  - Role sets: ADMIN_ROLES, TENANT_ADMIN_ROLES, PM_ROLES, RLS_BYPASS_ROLES
  - New auth guards: require_global_admin(), require_tenant_admin_or_above(),
    require_pm_or_above(), is_admin(), is_privileged()
  - Legacy require_admin / require_admin_or_pm now check both old+new roles
  - Migration 049: ADD VALUE global_admin + tenant_admin with AUTOCOMMIT
    workaround; backfills admin → global_admin
  - Seed: new admin users created with global_admin role

Phase 4.3 — RLS bypass updated for global_admin in get_db + set_tenant_context

Phase 4.4 — Tenant Feature Flags:
  - Migration 050: tenant_config JSONB on tenants table
  - Tenant model: tenant_config field + get_config() accessor
  - Defaults: max_concurrent_renders=3, fallback_material, invoice_prefix etc.

Phase 5.1 — Fallback Material:
  - blender_render.py: replace PALETTE_LINEAR/PALETTE_HEX/_assign_palette_material
    with _assign_failed_material() → SCHAEFFLER_059999_FailedMaterial (magenta)
  - Unmatched parts now logged explicitly before rendering

Phase 5.2 — Remove EEVEE fallback:
  - render_blender.py: EEVEE→Cycles silent retry removed; hard failure on EEVEE error

Phase 5.3 — Remove Blender version check:
  - render_blender.py: deleted MIN_BLENDER_VERSION = (5, 0, 1) constant

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

backend/app/utils/auth.py

@@ -59,14 +59,68 @@ async def get_current_user(
     return user
 
 
+def _role_value(user: User) -> str:
+    """Return the string value of a user's role (works for both enum and plain str)."""
+    role = user.role
+    return role.value if hasattr(role, "value") else str(role)
+
+
+# ── New role-hierarchy guards ─────────────────────────────────────────────────
+
+async def require_global_admin(user: User = Depends(get_current_user)) -> User:
+    """GlobalAdmin only (platform operator). Replaces require_admin() for new code."""
+    from app.domains.auth.models import ADMIN_ROLES
+    if _role_value(user) not in ADMIN_ROLES:
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Global admin access required")
+    return user
+
+
+async def require_tenant_admin_or_above(user: User = Depends(get_current_user)) -> User:
+    """TenantAdmin, GlobalAdmin, or legacy admin."""
+    from app.domains.auth.models import TENANT_ADMIN_ROLES
+    if _role_value(user) not in TENANT_ADMIN_ROLES:
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Tenant admin access required")
+    return user
+
+
+async def require_pm_or_above(user: User = Depends(get_current_user)) -> User:
+    """ProjectManager, TenantAdmin, GlobalAdmin, or legacy admin."""
+    from app.domains.auth.models import PM_ROLES
+    if _role_value(user) not in PM_ROLES:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="Project manager or above access required",
+        )
+    return user
+
+
+def is_admin(user: User) -> bool:
+    """Helper: True if user has any admin-level role."""
+    from app.domains.auth.models import ADMIN_ROLES
+    return _role_value(user) in ADMIN_ROLES
+
+
+def is_privileged(user: User) -> bool:
+    """Helper: True if user can manage orders/renders (PM or above)."""
+    from app.domains.auth.models import PM_ROLES
+    return _role_value(user) in PM_ROLES
+
+
+# ── Legacy guards (kept for backward compatibility) ───────────────────────────
+# These now accept both old ("admin") and new ("global_admin") roles.
+
 async def require_admin(user: User = Depends(get_current_user)) -> User:
-    if user.role.value != "admin":
+    """Backward-compat alias for require_global_admin(). Prefer require_global_admin() in new code."""
+    from app.domains.auth.models import ADMIN_ROLES
+    if _role_value(user) not in ADMIN_ROLES:
         raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Admin access required")
     return user
 
 
 async def require_admin_or_pm(user: User = Depends(get_current_user)) -> User:
-    if user.role.value not in ("admin", "project_manager"):
+    """Backward-compat alias for require_pm_or_above(). Prefer require_pm_or_above() in new code."""
+    from app.domains.auth.models import PM_ROLES
+    if _role_value(user) not in PM_ROLES:
         raise HTTPException(
             status_code=status.HTTP_403_FORBIDDEN,
             detail="Admin or Project Manager access required",