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/schemas/upload.py

@@ -1,43 +1,3 @@
-from pydantic import BaseModel
-from typing import Any
-
-
-class ParsedComponent(BaseModel):
-    part_name: str | None = None
-    material: str | None = None
-    component_type: str | None = None
-    column_index: int
-
-
-class ParsedRow(BaseModel):
-    row_index: int
-    ebene1: str | None = None
-    ebene2: str | None = None
-    baureihe: str | None = None
-    pim_id: str | None = None
-    produkt_baureihe: str | None = None
-    gewaehltes_produkt: str | None = None
-    name_cad_modell: str | None = None
-    gewuenschte_bildnummer: str | None = None
-    lagertyp: str | None = None
-    medias_rendering: bool | None = None
-    components: list[ParsedComponent] = []
-
-
-class ParsedExcelResponse(BaseModel):
-    filename: str
-    excel_path: str | None = None   # server-side path of the saved file
-    category_key: str | None = None
-    template_name: str | None = None
-    row_count: int
-    column_headers: list[str]
-    rows: list[ParsedRow]
-    warnings: list[str] = []
-
-
-class StepUploadResponse(BaseModel):
-    cad_file_id: str
-    original_name: str
-    file_hash: str
-    status: str
-    matched_items: list[str] = []
+# Compat shim — use app.domains.imports.schemas instead
+from app.domains.imports.schemas import ParsedComponent, ParsedRow, ParsedExcelResponse, StepUploadResponse
+__all__ = ["ParsedComponent", "ParsedRow", "ParsedExcelResponse", "StepUploadResponse"]