docs: add badges to readmes (#599)

shows the latest versions and a link to npm

packages/core/README.md

@@ -1,5 +1,7 @@
 # mosaic-core
 
+[![npm version](https://img.shields.io/npm/v/@uwdata/mosaic-core.svg)](https://www.npmjs.com/package/@uwdata/mosaic-core)
+
 The core Mosaic components: a central coordinator, parameters (`Param`) and selections (`Selection`) for linking scalar values or query predicates (respectively) across Mosaic clients, and filter groups with materialized views of pre-aggregated data. The Mosaic coordinator can send queries either over the network to a backing server (`socket` and `rest` clients) or to a client-side [DuckDB-WASM](https://github.com/duckdb/duckdb-wasm) instance (`wasm` client).
 
 The `mosaic-core` facilities are included as part of the [vgplot](https://github.com/uwdata/mosaic/tree/main/packages/vgplot) API.

packages/duckdb/README.md

@@ -1,5 +1,7 @@
 # mosaic-duckdb
 
+[![npm version](https://img.shields.io/npm/v/@uwdata/mosaic-duckdb.svg)](https://www.npmjs.com/package/@uwdata/mosaic-duckdb)
+
 A Promise-based Node.js API to DuckDB, along with a data server that supports transfer of [Apache Arrow](https://arrow.apache.org/) and JSON data over either Web Sockets or HTTP.
 
 _Warning_: Due to persistent quality issues involving the Node.js DuckDB client and Arrow extension, we recommend using the Python-based [`duckdb-server`](https://github.com/uwdata/mosaic/tree/main/packages/duckdb-server) package instead. However, we retain this package for both backwards compatibility and potential future use as quality issues improve.

packages/inputs/README.md

@@ -1,5 +1,7 @@
 # mosaic-inputs
 
+[![npm version](https://img.shields.io/npm/v/@uwdata/mosaic-inputs.svg)](https://www.npmjs.com/package/@uwdata/mosaic-inputs)
+
 Standalone data-driven components such as input menus, text search boxes, and sortable, load-on-scroll data tables. Input widgets integrate with Mosaic Params and Selections, and can either be used in a standalone fashion or draw values from a backing data table.
 
 The `mosaic-inputs` package is included as part of the [vgplot](https://github.com/uwdata/mosaic/tree/main/packages/vgplot) API.

packages/plot/README.md

@@ -1,5 +1,7 @@
 # mosaic-plot
 
+[![npm version](https://img.shields.io/npm/v/@uwdata/mosaic-plot.svg)](https://www.npmjs.com/package/@uwdata/mosaic-plot)
+
 A Mosaic-powered grammar of graphics based on [Observable Plot](https://github.com/observablehq/plot). Mmarks (plot layers) serve as individual Mosaic clients. These marks can push data processing (binning, hex binning, regression) and optimizations (such as M4 for line/area charts) down to the database. This package also provides interactors for linked selection, filtering, and highlighting using Mosaic Params and Selections.
 
 The `mosaic-plot` package is included as part of the [vgplot](https://github.com/uwdata/mosaic/tree/main/packages/vgplot) API.

packages/spec/README.md

@@ -1,5 +1,7 @@
 # mosaic-spec
 
+[![npm version](https://img.shields.io/npm/v/@uwdata/mosaic-spec.svg)](https://www.npmjs.com/package/@uwdata/mosaic-spec)
+
 Declarative specification of Mosaic-powered applications as JSON or YAML files. This package provides a parser and code generation framework for reading specifications in a JSON format and generating live Mosaic visualizations and dashboards using the [vgplot](https://github.com/uwdata/mosaic/tree/main/packages/vgplot) API.
 
 ## Usage

packages/sql/README.md

@@ -1,5 +1,7 @@
 # mosaic-sql
 
+[![npm version](https://img.shields.io/npm/v/@uwdata/mosaic-sql.svg)](https://www.npmjs.com/package/@uwdata/mosaic-sql)
+
 An API for convenient construction and analysis of SQL queries. Query objects then coerce to SQL query strings.
 
 Many `mosaic-sql` utilities are included as part of the [vgplot](https://github.com/uwdata/mosaic/tree/main/packages/vgplot) API.

packages/vgplot/README.md

@@ -1,5 +1,7 @@
 # vgplot: A Mosaic-powered Visualization Grammar
 
+[![npm version](https://img.shields.io/npm/v/@uwdata/vgplot.svg)](https://www.npmjs.com/package/@uwdata/vgplot)
+
 A **v**isualization **g**rammar for interactive Mosaic-powered visualizations and dashboards. This package provides convenient, composable methods that combines multiple Mosaic packages (core, inputs, plot, etc.) in an integrated API.
 
 vgplot is a JavaScript API for creating visualizations and dashboards. See the [mosaic-spec](https://github.com/uwdata/mosaic/tree/main/packages/spec) package to instead use declarative specifications in JSON or YAML format.