Add CI workflow and README badges

CI runs on Node 18/20/22 for push and PRs.
Badges: npm version, CI status, MIT license.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: albertdobmeyer

.github/workflows/ci.yml

@@ -0,0 +1,22 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [18, 20, 22]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+      - run: node token-meter.mjs --help
+      - run: node token-meter.mjs --agents
+      - run: npm pack --dry-run

README.md

@@ -1,5 +1,7 @@
 # Agent Token Meter
 
+[![npm version](https://img.shields.io/npm/v/agent-token-meter)](https://www.npmjs.com/package/agent-token-meter) [![CI](https://github.com/albertdobmeyer/agent-token-meter/actions/workflows/ci.yml/badge.svg)](https://github.com/albertdobmeyer/agent-token-meter/actions/workflows/ci.yml) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
 **A speedometer for your context window.** Zero dependencies. Single file. Answers one question: *should I reset my context right now?*
 
 AI coding agents bill by tokens, and conversations accumulate cost **quadratically** — each message resends the entire history. A 100-turn conversation doesn't cost 10x more than a 10-turn conversation. It costs **50x** more. Most developers have no real-time visibility into this.