Add QWEN.md with project documentation and architecture overview

Author: jbruwes

QWEN.md

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+# flat-json-tree Project Context
+
+## Project Overview
+
+`flat-json-tree` is a TypeScript library that provides a simple way to manipulate JSON tree objects. The core idea is to transform a JSON tree object into a flat array, allowing standard array operations like `find`, `findIndex`, `filter`, `map`, and others. It's built as a Vue 3 composable function.
+
+The library is published as `@vuebro/flat-json-tree` with the current version being 2.1.12. It's designed to work with tree structures where each element has a unique identifier field.
+
+The project follows the AGPL-3.0 license and is maintained by Jerry Bruwes.
+
+## Architecture and Implementation
+
+The library transforms a JSON tree into a flat array while preserving the tree structure through computed properties added to each child object:
+- `branch`: Array of objects representing the path from root to current node
+- `index`: Index of the object in the sibling array
+- `next`: Next object in the sibling array
+- `parent`: Parent object
+- `prev`: Previous object in the sibling array
+- `siblings`: Array of sibling objects
+
+The main implementation is in `src/index.ts` as a default export function that takes a tree and optional configuration object, returning a composable with reactive properties and manipulation functions.
+
+## Building and Running
+
+### Prerequisites
+- Node.js and npm
+
+### Build Process
+To build the project:
+```bash
+npm run build
+```
+This command uses TypeScript compiler (tsc) to compile the source code.
+
+### Linting
+To lint the code:
+```bash
+npm run lint
+```
+
+### Development Setup
+1. Clone the repository
+2. Run `npm install` to install dependencies
+3. Run `npm run build` to build the project
+
+## Key Features and API
+
+### Main Function
+`useFlatJsonTree(tree, options?)` - The main composable function with the following return value:
+- `nodes`: ComputedRef with the flat array of objects
+- `nodesMap`: ComputedRef with an object mapping unique IDs to objects
+- Manipulation functions: `add`, `addChild`, `remove`, `down`, `left`, `right`, `up`
+
+### Manipulation Functions
+- `add`: Add an empty object to the siblings
+- `addChild`: Add an empty object to the children
+- `remove`: Remove an object from the tree
+- `down`: Move an object down by one position
+- `left`: Move an object left by one position
+- `right`: Move an object right by one position
+- `up`: Move an object up by one position
+
+## Development Conventions
+
+### Coding Style
+- The project uses TypeScript with Vue 3 reactivity
+- Follows ESLint linting rules defined in `@vuebro/configs/eslint`
+- TypeScript configuration extends `@vuebro/configs/tsconfig`
+- Uses Prettier formatting with `@vuebro/configs/prettierrc` configuration
+
+### File Structure
+- `src/index.ts`: Main implementation file
+- `dist/`: Compiled output directory
+- Configuration files at root level (eslint.config.ts, tsconfig.json, etc.)
+
+### Dependencies
+- Vue 3 (reactivity system) as main dependency
+- Development dependencies include TypeScript, Node types, and VueBro configuration packages