Add standalone Hwacheon network viewer

.gitignore

@@ -0,0 +1,51 @@
+# Python and local runtime output
+__pycache__/
+*.py[cod]
+.venv/
+venv/
+*.log
+*.pid
+.local/
+test-results/
+playwright-report/
+.pytest_cache/
+.coverage
+htmlcov/
+
+# Credentials and machine-specific settings
+.env
+.env.*
+!.env.example
+*.pem
+*.key
+*.p12
+*.pfx
+*credentials*
+*secrets*
+.aws/
+.ssh/
+.codex/
+.agents/
+.vscode/
+.idea/
+
+# Source drawings are not part of this runtime submission.
+# web/data/network.json MUST remain included: the viewer needs it.
+drawings/
+references/
+*.inp
+*.INP
+*.dxf
+*.DXF
+*.pdf
+*.PDF
+
+# Temporary and platform files
+*.tmp
+*.temp
+*.bak
+*.swp
+*~
+.DS_Store
+Thumbs.db
+node_modules/