✨ feat: add SQLite persistence, multi-tenancy, auto-sync, and CI/Docker improvements (#1)

Replace in-memory storage with SQLite (WAL mode), add workspace-based
multi-tenancy with auto-detection via server.listRoots(), and embed the
canvas server into the MCP process for single-process operation.

🔧 Core enhancements:
- SQLite persistence with versioning, element history, and search
- Multi-tenancy: isolated canvases per workspace (SHA-256 tenant IDs)
- Embedded canvas lifecycle (single node process starts MCP + canvas)
- Auto-sync with 3s debounce and manual override toggle
- Configurable canvas port via CANVAS_PORT env var
- 6 new MCP tools (search, history, tenants, projects)
- Workspace switcher UI with dropdown search
- Sync normalization to prevent bound-text breakage on reload

🐳 Docker & CI improvements:
- BuildKit cache mounts for faster npm installs across builds
- Skip native compilation in frontend-builder stage (--ignore-scripts)
- Build only linux/amd64 on PRs, multi-arch on push to main
- Docker Hub registry with proper build tools for better-sqlite3
- CI and Docker status check gates (github/ci-status-check, github/docker-build-check)

📦 Package & publishing:
- Renamed to @sanjibdevnath/mcp-excalidraw-local (v3.0.0)
- Updated npm-publish workflow for scoped package
- Updated bin entry, keywords, and files list

📝 Documentation:
- README with UI screenshots, architecture diagram, and full feature docs
- Updated agent skill with 32-tool cheatsheet and workflow playbooks
- Fork attribution and upstream comparison table

Co-authored-by: Cursor <cursoragent@cursor.com>

Dockerfile.canvas

@@ -1,82 +1,62 @@
 # Dockerfile for Canvas Server (Optional)
-# This is for users who want to run the visual canvas UI
-# The canvas server provides the web interface and REST API
+# Provides the web interface, REST API, and SQLite persistence
 
 # Stage 1: Build frontend
 FROM node:18-slim AS frontend-builder
 
 WORKDIR /app
 
-# Copy package files
 COPY package*.json ./
+RUN --mount=type=cache,target=/root/.npm npm ci --ignore-scripts
 
-# Install all dependencies (including dev dependencies for build)
-RUN npm ci && npm cache clean --force
-
-# Copy frontend source
 COPY frontend ./frontend
 COPY vite.config.js ./
-
-# Build frontend
 RUN npm run build:frontend
 
-# Stage 2: Build backend (TypeScript compilation)
+# Stage 2: Build backend (TypeScript compilation + native modules)
 FROM node:18-slim AS backend-builder
 
+RUN apt-get update && apt-get install -y python3 make g++ && rm -rf /var/lib/apt/lists/*
+
 WORKDIR /app
 
-# Copy package files
 COPY package*.json ./
+RUN --mount=type=cache,target=/root/.npm npm ci
 
-# Install all dependencies (including TypeScript compiler)
-RUN npm ci && npm cache clean --force
-
-# Copy backend source
 COPY src ./src
 COPY tsconfig.json ./
-
-# Compile TypeScript
 RUN npm run build:server
 
 # Stage 3: Production Canvas Server
 FROM node:18-slim AS production
 
-# Create non-root user for security
+RUN apt-get update && apt-get install -y python3 make g++ && rm -rf /var/lib/apt/lists/*
+
 RUN addgroup --system --gid 1001 nodejs && \
     adduser --system --uid 1001 --gid 1001 nodejs
 
 WORKDIR /app
 
-# Copy package files
 COPY package*.json ./
+RUN --mount=type=cache,target=/root/.npm npm ci --omit=dev
 
-# Install only production dependencies
-RUN npm ci --only=production && npm cache clean --force
+# Remove build tools after native modules are compiled
+RUN apt-get purge -y python3 make g++ && apt-get autoremove -y
 
-# Copy compiled backend from builder stage
 COPY --from=backend-builder /app/dist ./dist
-
-# Copy built frontend from frontend-builder stage
 COPY --from=frontend-builder /app/dist/frontend ./dist/frontend
 
-# Set ownership to nodejs user
 RUN chown -R nodejs:nodejs /app
-
-# Switch to non-root user
 USER nodejs
 
-# Set environment variables with defaults
 ENV NODE_ENV=production
 ENV PORT=3000
 ENV HOST=0.0.0.0
 
-# Expose port
 EXPOSE 3000
 
-# Run canvas server (web UI + REST API)
 CMD ["node", "dist/server.js"]
 
-# Labels for metadata
-LABEL org.opencontainers.image.source="https://github.com/yctimlin/mcp_excalidraw"
-LABEL org.opencontainers.image.description="MCP Excalidraw Canvas Server - Web UI and REST API"
+LABEL org.opencontainers.image.source="https://github.com/sanjibdevnathlabs/mcp-excalidraw-local"
+LABEL org.opencontainers.image.description="MCP Excalidraw Canvas Server - Web UI and REST API (with SQLite persistence & multi-tenancy)"
 LABEL org.opencontainers.image.licenses="MIT"