Add memory-viewer from silicondawn

- Web UI for browsing and editing OpenClaw memory files
- Cloned from https://github.com/silicondawn/memory-viewer
- Built and running on port 8901
- Features: file tree, markdown rendering, search, live reload
- Full access to MEMORY.md, daily notes, skills, automations

memory-viewer/.dockerignore

@@ -0,0 +1,16 @@
+node_modules
+npm-debug.log
+.git
+.gitignore
+README.zh-CN.md
+CONTRIBUTING.md
+LICENSE
+docs
+.env
+.nyc_output
+coverage
+.DS_Store
+*.log
+
+# Keep CHANGELOG.md - it's imported by src/components/Changelog.tsx
+# CHANGELOG.md