refactor(B1): migrate to domain-driven project structure

Move all models/schemas/services/routers into app/domains/.
Keep backward-compat shims in old locations for imports.
Preserves domains/rendering/tasks.py from Phase A.

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

backend/app/services/template_service.py

@@ -1,102 +1,3 @@
-"""Render template resolution service.
-
-Used from Celery tasks (sync context) to find the best matching .blend template
-for a given category + output type combination.
-
-Cascade priority (first active match wins):
-1. Exact:         category_key + output_type_id
-2. Category only: category_key + output_type_id IS NULL
-3. OT only:       category_key IS NULL + output_type_id
-4. Global:        both NULL
-5. No template  → caller falls back to factory-settings behavior
-"""
-import logging
-
-from sqlalchemy import create_engine, select, and_
-from sqlalchemy.orm import Session
-
-from app.models.render_template import RenderTemplate
-from app.models.system_setting import SystemSetting
-
-logger = logging.getLogger(__name__)
-
-_engine = None
-
-
-def _get_engine():
-    global _engine
-    if _engine is None:
-        from app.config import settings as app_settings
-        _engine = create_engine(app_settings.database_url_sync)
-    return _engine
-
-
-def resolve_template(
-    category_key: str | None = None,
-    output_type_id: str | None = None,
-) -> RenderTemplate | None:
-    """Find the best matching active render template.
-
-    Uses sync SQLAlchemy — safe for Celery tasks.
-    """
-    engine = _get_engine()
-    with Session(engine) as session:
-        active = RenderTemplate.is_active == True  # noqa: E712
-
-        # 1. Exact match
-        if category_key and output_type_id:
-            row = session.execute(
-                select(RenderTemplate).where(and_(
-                    active,
-                    RenderTemplate.category_key == category_key,
-                    RenderTemplate.output_type_id == output_type_id,
-                ))
-            ).scalar_one_or_none()
-            if row:
-                return row
-
-        # 2. Category only
-        if category_key:
-            row = session.execute(
-                select(RenderTemplate).where(and_(
-                    active,
-                    RenderTemplate.category_key == category_key,
-                    RenderTemplate.output_type_id.is_(None),
-                ))
-            ).scalar_one_or_none()
-            if row:
-                return row
-
-        # 3. OT only
-        if output_type_id:
-            row = session.execute(
-                select(RenderTemplate).where(and_(
-                    active,
-                    RenderTemplate.category_key.is_(None),
-                    RenderTemplate.output_type_id == output_type_id,
-                ))
-            ).scalar_one_or_none()
-            if row:
-                return row
-
-        # 4. Global fallback (both NULL)
-        row = session.execute(
-            select(RenderTemplate).where(and_(
-                active,
-                RenderTemplate.category_key.is_(None),
-                RenderTemplate.output_type_id.is_(None),
-            ))
-        ).scalar_one_or_none()
-        return row
-
-
-def get_material_library_path() -> str | None:
-    """Read material_library_path from system_settings. Returns None if empty."""
-    engine = _get_engine()
-    with Session(engine) as session:
-        row = session.execute(
-            select(SystemSetting).where(SystemSetting.key == "material_library_path")
-        ).scalar_one_or_none()
-        if row and row.value and row.value.strip():
-            return row.value.strip()
-        return None
+# Compat shim — use app.domains.rendering.service instead
+from app.domains.rendering.service import resolve_template, get_material_library_path
+__all__ = ["resolve_template", "get_material_library_path"]