feat(dwg): DWG→DXF via sidecar microservice (libredwg)

Add dedicated dwg2dxf container (Debian slim + libredwg-tools + Flask)
instead of modifying the Alpine base image. The ArchiTools API route
proxies to the sidecar over Docker internal network.

- dwg2dxf-api/: Dockerfile + Flask app (POST /convert, GET /health)
- docker-compose.yml: dwg2dxf service, healthcheck, depends_on
- route.ts: rewritten from local exec to HTTP proxy
- .dockerignore: exclude sidecar from main build context

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

dwg2dxf-api/app.py

@@ -0,0 +1,93 @@
+"""Minimal DWG-to-DXF conversion microservice via libredwg."""
+
+import os
+import subprocess
+import tempfile
+import uuid
+
+from flask import Flask, request, send_file, jsonify
+
+app = Flask(__name__)
+
+MAX_FILE_SIZE = 100 * 1024 * 1024  # 100 MB
+
+
+@app.route("/health", methods=["GET"])
+def health():
+    """Health check — verifies dwg2dxf binary is callable."""
+    try:
+        subprocess.run(["dwg2dxf", "--version"], capture_output=True, timeout=5)
+        return jsonify({"status": "ok", "dwg2dxf": "available"}), 200
+    except Exception as e:
+        return jsonify({"status": "error", "detail": str(e)}), 503
+
+
+@app.route("/convert", methods=["POST"])
+def convert():
+    """Accept a DWG file via multipart upload, return DXF."""
+    if "file" not in request.files:
+        return jsonify({"error": "Missing 'file' field in upload."}), 400
+
+    uploaded = request.files["file"]
+    original_name = uploaded.filename or "input.dwg"
+
+    if not original_name.lower().endswith(".dwg"):
+        return jsonify({"error": "File must have .dwg extension."}), 400
+
+    safe_name = "".join(
+        c if c.isalnum() or c in "._-" else "_" for c in original_name
+    )
+
+    tmp_dir = os.path.join(tempfile.gettempdir(), f"dwg-{uuid.uuid4().hex}")
+    os.makedirs(tmp_dir, exist_ok=True)
+
+    input_path = os.path.join(tmp_dir, safe_name)
+    output_path = input_path.rsplit(".", 1)[0] + ".dxf"
+
+    try:
+        uploaded.save(input_path)
+
+        file_size = os.path.getsize(input_path)
+        if file_size > MAX_FILE_SIZE:
+            return jsonify({"error": f"File too large ({file_size} bytes)."}), 413
+
+        result = subprocess.run(
+            ["dwg2dxf", input_path],
+            capture_output=True,
+            timeout=120,
+        )
+
+        if not os.path.exists(output_path):
+            stderr = result.stderr.decode("utf-8", errors="replace")
+            return jsonify({
+                "error": f"Conversion failed: {stderr or 'no output file'}"
+            }), 500
+
+        dxf_name = safe_name.rsplit(".", 1)[0] + ".dxf"
+        return send_file(
+            output_path,
+            mimetype="application/dxf",
+            as_attachment=True,
+            download_name=dxf_name,
+        )
+
+    except subprocess.TimeoutExpired:
+        return jsonify({"error": "Conversion timed out (120s limit)."}), 504
+
+    except Exception as e:
+        return jsonify({"error": f"Unexpected error: {str(e)}"}), 500
+
+    finally:
+        for f in os.listdir(tmp_dir):
+            try:
+                os.unlink(os.path.join(tmp_dir, f))
+            except OSError:
+                pass
+        try:
+            os.rmdir(tmp_dir)
+        except OSError:
+            pass
+
+
+if __name__ == "__main__":
+    app.run(host="0.0.0.0", port=5001)