fix: Add appsettings.Production.json generation to deploy-prod.yml

Missing configuration file step caused DB authentication failure.
Added Python config generator (taxbaik pattern) to create
appsettings.Production.json with DB connection string before packaging.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

.gitea/workflows/deploy-prod.yml

@@ -64,6 +64,36 @@ jobs:
             --no-restore \
             --no-build
 
+      - name: Write Production Config
+        run: |
+          mkdir -p ./publish
+          DEPLOY_HOST="${{ secrets.DEPLOY_HOST }}"
+          DEPLOY_USER="${{ secrets.DEPLOY_USER }}"
+
+          # appsettings.Production.json 생성
+          python3 -c '
+          import json
+          import pathlib
+
+          config = {
+            "ConnectionStrings": {
+              "DefaultConnection": "Host=127.0.0.1;Database=quantenginedb;Username=quantengine_app;Password=quantengine_app;Search Path=quantengine;"
+            },
+            "Logging": {
+              "LogLevel": {
+                "Default": "Information"
+              }
+            }
+          }
+
+          pathlib.Path("./publish/appsettings.Production.json").write_text(
+            json.dumps(config, ensure_ascii=False, indent=2),
+            encoding="utf-8"
+          )'
+
+          test -s ./publish/appsettings.Production.json || { echo "ERROR: appsettings.Production.json is empty"; exit 1; }
+          echo "✓ Production config created"
+
       - name: Package Artifact
         run: |
           ARTIFACT="${{ steps.metadata.outputs.artifact }}"