Copilot cost calculation module

[DinahK-2SO]

The copilot cli cost calculation module.

Demo:

1. launch copilot

copilot --allow-all-tools --output-format json --session-id $sid

2. interact with copilot. For instance,

"You MUST use the 'task' tool to launch exactly 3 sub-agents in parallel in a single turn. " +
          "Give each one this exact instruction: 'Reply with one line: WORKER OK'. " +
          "Do not do the work yourself. After all three return, print: ALL DONE."

3. in copilot cli, use /usage to see what is actual shown in copilot-cli /usage:

4. get module calculation:

$events = Join-Path $env:USERPROFILE ".copilot/session-state/$sid/events.jsonl"
cd <win-dev-skills>\src\tools\cost-module

node -e "import('./src/copilot-cost.ts').then(async m => console.log(m.formatReport(await m.analyzeJsonlFile(process.argv[1]))))" $events