feat: replace Python seam carving with caire Go binary

Replace the Python seam-carving library with caire (esimov/caire v1.5.0),
a Go-based content-aware resize engine that is faster and supports both
shrinking and enlarging via seam insertion.

- Add Go builder stage in Dockerfile to compile caire from source
- Rewrite seam-carving.ts to call caire via execFile (no Python sidecar)
- Remove content-aware-resize from PYTHON_SIDECAR_TOOLS (60s timeout)
- Add new options: blur radius, edge sensitivity, square mode, face detection
- Move content-aware toggle below standard resize in UI (subtler placement)
- Rename "Don't enlarge" to "Limit to original size" with hover tooltip
- Add smooth progress bar for medium-duration tools
- Delete seam_carve.py and remove seam-carving pip dependency
- Update integration tests and visual regression screenshots

docker/Dockerfile

@@ -36,13 +36,27 @@ RUN --mount=type=cache,id=turbo-cache,target=/app/.turbo \
     pnpm --filter @stirling-image/web build
 
 # ============================================
-# Stage 2: Platform-specific base images
+# Stage 2: Build caire (content-aware resize)
+# ============================================
+FROM golang:1.23-bookworm AS caire-builder
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libwayland-dev libx11-dev libx11-xcb-dev libxkbcommon-x11-dev \
+    libgles2-mesa-dev libegl1-mesa-dev libffi-dev libxcursor-dev \
+    libxrandr-dev libxinerama-dev libxi-dev libxxf86vm-dev \
+    libvulkan-dev libxfixes-dev pkg-config \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN go install github.com/esimov/caire/cmd/caire@v1.5.0
+
+# ============================================
+# Stage 3: Platform-specific base images
 # ============================================
 FROM node:22-bookworm AS base-linux-arm64
 FROM nvidia/cuda:12.6.3-runtime-ubuntu24.04 AS base-linux-amd64
 
 # ============================================
-# Stage 3: Production runtime
+# Stage 4: Production runtime
 # ============================================
 ARG TARGETOS
 ARG TARGETARCH
@@ -78,8 +92,13 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     tesseract-ocr tesseract-ocr-eng tesseract-ocr-deu tesseract-ocr-fra tesseract-ocr-spa \
     build-essential \
     libgl1 libglib2.0-0 \
+    libegl1 libwayland-egl1 libwayland-client0 libwayland-cursor0 \
+    libxkbcommon-x11-0 libxkbcommon0 libxcursor1 \
     && rm -rf /var/lib/apt/lists/*
 
+# Caire binary (content-aware seam carving)
+COPY --from=caire-builder /go/bin/caire /usr/local/bin/caire
+
 # Python venv - Layer 1: Base packages (rarely change, ~3 GB)
 RUN python3 -m venv /opt/venv && \
     /opt/venv/bin/pip install --upgrade pip && \
@@ -116,8 +135,6 @@ RUN if [ "$TARGETARCH" = "amd64" ]; then \
     /opt/venv/bin/pip install mediapipe==0.10.18 \
 ; fi
 
-RUN /opt/venv/bin/pip install seam-carving==1.1.0
-
 # Pre-download and verify all ML models
 # Note: on amd64, paddlepaddle-gpu can't import without the CUDA driver (only
 # available at runtime). The download script gracefully skips PaddleOCR model