fix: Restore all files lost during destructive rebase

A previous `git pull --rebase origin main` dropped 177 local commits,
losing 3400+ files across admin-v2, backend, studio-v2, website,
klausur-service, and many other services. The partial restore attempt
(660295e2) only recovered some files.

This commit restores all missing files from pre-rebase ref 98933f5e
while preserving post-rebase additions (night-scheduler, night-mode UI,
NightModeWidget dashboard integration).

Restored features include:
- AI Module Sidebar (FAB), OCR Labeling, OCR Compare
- GPU Dashboard, RAG Pipeline, Magic Help
- Klausur-Korrektur (8 files), Abitur-Archiv (5+ files)
- Companion, Zeugnisse-Crawler, Screen Flow
- Full backend, studio-v2, website, klausur-service
- All compliance SDKs, agent-core, voice-service
- CI/CD configs, documentation, scripts

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

backend/Dockerfile

@@ -0,0 +1,63 @@
+# Build stage
+FROM python:3.12-slim-bookworm AS builder
+
+WORKDIR /app
+
+# Install build dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    build-essential \
+    libpq-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy requirements first for better caching
+COPY requirements.txt .
+
+# Create virtual environment and install dependencies
+RUN python -m venv /opt/venv
+ENV PATH="/opt/venv/bin:$PATH"
+RUN pip install --no-cache-dir --upgrade pip && \
+    pip install --no-cache-dir -r requirements.txt
+
+# Runtime stage
+FROM python:3.12-slim-bookworm
+
+WORKDIR /app
+
+# Install runtime dependencies for WeasyPrint and OpenCV
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libpango-1.0-0 \
+    libpangocairo-1.0-0 \
+    libgdk-pixbuf-2.0-0 \
+    libffi-dev \
+    shared-mime-info \
+    libgl1 \
+    libglib2.0-0 \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy virtual environment from builder
+COPY --from=builder /opt/venv /opt/venv
+ENV PATH="/opt/venv/bin:$PATH"
+
+# Create non-root user
+RUN useradd --create-home --shell /bin/bash appuser
+
+# Copy application code
+COPY --chown=appuser:appuser . .
+
+# Switch to non-root user
+USER appuser
+
+# Environment variables
+ENV PYTHONUNBUFFERED=1
+ENV PYTHONDONTWRITEBYTECODE=1
+
+# Expose port
+EXPOSE 8000
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
+    CMD curl -f http://localhost:8000/api/consent/health || exit 1
+
+# Run the application
+CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]