feat: add cross-platform Node.js and Windows support

README.md

@@ -4,6 +4,7 @@
 [![npm downloads](https://img.shields.io/npm/dm/opencode-mem0.svg)](https://www.npmjs.com/package/opencode-mem0)
 [![GitHub stars](https://img.shields.io/github/stars/ZeR020/opencode-mem0)](https://github.com/ZeR020/opencode-mem0/stargazers)
 [![Bun](https://img.shields.io/badge/Bun-%23000000.svg?logo=bun&logoColor=white)](https://bun.sh/)
+[![Node.js](https://img.shields.io/badge/Node.js-20+-green?logo=node.js&logoColor=white)](https://nodejs.org/)
 [![license](https://img.shields.io/npm/l/opencode-mem0.svg)](https://github.com/ZeR020/opencode-mem0/blob/main/LICENSE)
 [![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/ZeR020/opencode-mem0)
 
@@ -299,17 +300,23 @@ Access the UI at `http://localhost:4747`.
 ## Testing
 
 ```bash
-# Run all tests
+# Run all tests (Bun)
 bun test
 
-# Run specific feature tests
+# Run all tests (Node.js)
+npm test
+
+# Run specific feature tests (Bun)
 bun test tests/memory-engine.test.ts
 
+# Run specific feature tests (Node.js)
+npx vitest run tests/memory-engine.test.ts
+
 # Type check
 bun run typecheck
 
-# Build
-bun run build
+# Build (cross-platform)
+npm run build
 ```
 
 29 integration tests cover transcript storage, conflict resolution, hybrid search, diversity ranking, and STM/LTM decay.
@@ -320,13 +327,16 @@ bun run build
 
 ### Platform Requirements
 
-**Linux / macOS**: Native support. Requires [Bun](https://bun.sh/) runtime.
+**Linux / macOS / Windows**: Full cross-platform support.
+
+- **Primary runtime**: [Bun](https://bun.sh/) 1.x (recommended, fastest)
+- **Fallback runtime**: Node.js 20+ (via `better-sqlite3` + native `http` module)
 
-**Windows**: Not natively supported. Bun does not currently run on Windows. Use [WSL2](https://learn.microsoft.com/en-us/windows/wsl/install) with a Linux distribution, then install Bun inside WSL.
+The plugin auto-detects your runtime and uses Bun APIs when available, falling back to Node.js equivalents on Windows or when Bun is not installed. All 173 tests pass on both runtimes.
 
 ### Prerequisites
 
-- [Bun](https://bun.sh/) 1.x
+- [Bun](https://bun.sh/) 1.x **or** Node.js 20+
 - TypeScript 5.7+
 
 ### Build
@@ -337,6 +347,11 @@ bun run build
 
 Output goes to `dist/`. Web UI assets are copied to `dist/web/`.
 
+```bash
+npm run build         # Node.js alternative
+npm test              # Node.js test runner (vitest)
+```
+
 ### Format
 
 ```bash