[split-required] Split remaining Python monoliths (Phase 1 continued)

klausur-service (7 monoliths):
- grid_editor_helpers.py (1,737 → 5 files: columns, filters, headers, zones)
- cv_cell_grid.py (1,675 → 7 files: build, legacy, streaming, merge, vocab)
- worksheet_editor_api.py (1,305 → 4 files: models, AI, reconstruct, routes)
- legal_corpus_ingestion.py (1,280 → 3 files: registry, chunking, ingestion)
- cv_review.py (1,248 → 4 files: pipeline, spell, LLM, barrel)
- cv_preprocessing.py (1,166 → 3 files: deskew, dewarp, barrel)
- rbac.py, admin_api.py, routes/eh.py remain (next batch)

backend-lehrer (1 monolith):
- classroom_engine/repository.py (1,705 → 7 files by domain)

All re-export barrels preserve backward compatibility.
Zero import errors verified.

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

klausur-service/backend/worksheet_editor_models.py

@@ -0,0 +1,133 @@
+"""
+Worksheet Editor Models — Enums, Pydantic models, and configuration.
+"""
+
+import os
+import logging
+from typing import Optional, List, Dict
+from enum import Enum
+
+from pydantic import BaseModel, Field
+
+logger = logging.getLogger(__name__)
+
+# =============================================
+# CONFIGURATION
+# =============================================
+
+OLLAMA_URL = os.getenv("OLLAMA_URL", "http://host.docker.internal:11434")
+SD_MODEL = os.getenv("SD_MODEL", "stable-diffusion")  # or specific SD model
+WORKSHEET_STORAGE_DIR = os.getenv("WORKSHEET_STORAGE_DIR",
+    os.path.join(os.path.dirname(os.path.abspath(__file__)), "worksheet-storage"))
+
+# Ensure storage directory exists
+os.makedirs(WORKSHEET_STORAGE_DIR, exist_ok=True)
+
+# =============================================
+# ENUMS & MODELS
+# =============================================
+
+class AIImageStyle(str, Enum):
+    REALISTIC = "realistic"
+    CARTOON = "cartoon"
+    SKETCH = "sketch"
+    CLIPART = "clipart"
+    EDUCATIONAL = "educational"
+
+class WorksheetStatus(str, Enum):
+    DRAFT = "draft"
+    PUBLISHED = "published"
+    ARCHIVED = "archived"
+
+# Style prompt modifiers
+STYLE_PROMPTS = {
+    AIImageStyle.REALISTIC: "photorealistic, high detail, professional photography",
+    AIImageStyle.CARTOON: "cartoon style, colorful, child-friendly, simple shapes",
+    AIImageStyle.SKETCH: "pencil sketch, hand-drawn, black and white, artistic",
+    AIImageStyle.CLIPART: "clipart style, flat design, simple, vector-like",
+    AIImageStyle.EDUCATIONAL: "educational illustration, clear, informative, textbook style"
+}
+
+# =============================================
+# REQUEST/RESPONSE MODELS
+# =============================================
+
+class AIImageRequest(BaseModel):
+    prompt: str = Field(..., min_length=3, max_length=500)
+    style: AIImageStyle = AIImageStyle.EDUCATIONAL
+    width: int = Field(512, ge=256, le=1024)
+    height: int = Field(512, ge=256, le=1024)
+
+class AIImageResponse(BaseModel):
+    image_base64: str
+    prompt_used: str
+    error: Optional[str] = None
+
+class PageData(BaseModel):
+    id: str
+    index: int
+    canvasJSON: str
+
+class PageFormat(BaseModel):
+    width: float = 210
+    height: float = 297
+    orientation: str = "portrait"
+    margins: Dict[str, float] = {"top": 15, "right": 15, "bottom": 15, "left": 15}
+
+class WorksheetSaveRequest(BaseModel):
+    id: Optional[str] = None
+    title: str
+    description: Optional[str] = None
+    pages: List[PageData]
+    pageFormat: Optional[PageFormat] = None
+
+class WorksheetResponse(BaseModel):
+    id: str
+    title: str
+    description: Optional[str]
+    pages: List[PageData]
+    pageFormat: PageFormat
+    createdAt: str
+    updatedAt: str
+
+class AIModifyRequest(BaseModel):
+    prompt: str = Field(..., min_length=3, max_length=1000)
+    canvas_json: str
+    model: str = "qwen2.5vl:32b"
+
+class AIModifyResponse(BaseModel):
+    modified_canvas_json: Optional[str] = None
+    message: str
+    error: Optional[str] = None
+
+class ReconstructRequest(BaseModel):
+    session_id: str
+    page_number: int = 1
+    include_images: bool = True
+    regenerate_graphics: bool = False
+
+class ReconstructResponse(BaseModel):
+    canvas_json: str
+    page_width: int
+    page_height: int
+    elements_count: int
+    vocabulary_matched: int
+    message: str
+    error: Optional[str] = None
+
+# =============================================
+# IN-MEMORY STORAGE (Development)
+# =============================================
+
+worksheets_db: Dict[str, Dict] = {}
+
+# PDF Generation availability
+try:
+    from reportlab.lib import colors  # noqa: F401
+    from reportlab.lib.pagesizes import A4  # noqa: F401
+    from reportlab.lib.units import mm  # noqa: F401
+    from reportlab.pdfgen import canvas  # noqa: F401
+    from reportlab.lib.styles import getSampleStyleSheet  # noqa: F401
+    REPORTLAB_AVAILABLE = True
+except ImportError:
+    REPORTLAB_AVAILABLE = False