Add floating canvas panels, theme settings, and SVG line-spacing analysis.

Canvas Studio now uses dockable floating panels, app settings/help navigation, and improved SVG export; the backend adds an SVG line-spacing analysis API with SciPy acceleration and new design templates.

backend/start-dev.sh

@@ -57,6 +57,32 @@ if [[ "$DEPS_OK" == "0" ]]; then
     "$PYTHON" -m pip install -q fastapi uvicorn python-multipart pydantic pandas openpyxl pillow numpy matplotlib
 fi
 
+# SciPy is an optional accelerator for line-spacing analysis. The production
+# requirements include it, but local dev environments may already have it in
+# the base interpreter while the project venv does not. Reuse that copy when
+# the Python ABI matches so startup does not require a network install.
+EXTRA_SCIPY_SITE=""
+if ! "$PYTHON" -c 'import scipy' >/dev/null 2>&1; then
+    PYTHON_ABI=$("$PYTHON" -c 'import sys; print(f"{sys.version_info.major}.{sys.version_info.minor}")')
+    for cmd in python3.13 python3.12 python3.11 python3.10 python3.9 python3; do
+        if command -v "$cmd" >/dev/null 2>&1; then
+            SCIPY_SITE=$("$cmd" -c '
+import pathlib
+import scipy
+import sys
+expected = "'"$PYTHON_ABI"'"
+current = f"{sys.version_info.major}.{sys.version_info.minor}"
+print(pathlib.Path(scipy.__file__).parents[1] if current == expected else "")
+' 2>/dev/null || true)
+            if [[ -n "$SCIPY_SITE" ]]; then
+                EXTRA_SCIPY_SITE="$SCIPY_SITE"
+                echo "[OK]    使用外部 SciPy 加速线距计算: $SCIPY_SITE"
+                break
+            fi
+        fi
+    done
+fi
+
 # ── C++ extension ────────────────────────────────────────
 EXT=$($PYTHON -c 'import importlib.machinery; print(importlib.machinery.EXTENSION_SUFFIXES[0])')
 EWC_SO="$ROOT_DIR/EfficientWordCloud/efficient_wordcloud/ewc_core${EXT}"
@@ -83,6 +109,7 @@ fi
 # ── start ────────────────────────────────────────────────
 echo "[INFO]  启动后端 http://0.0.0.0:${BACKEND_PORT}"
 
+WORDCLOUD_SCIPY_SITE="$EXTRA_SCIPY_SITE" \
 PYTHONPATH="$ROOT_DIR/EfficientWordCloud" \
     "$PYTHON" -m uvicorn service.app:app \
     --app-dir "$ROOT_DIR" \