Add command to view results of a previous test run

## Problem

After running a test, the only way to view results is to manually inspect files in the results directory. The `--html` and `--openHtml` flags only work at test time — there's no way to generate or open a report for a previously completed test.

## Expected behavior

A command like `npx telescope --open ` (or similar) that generates and opens an HTML report from existing results.

## Current workaround

Manually open individual files (`metrics.json`, `screenshot.png`, `pageload.har`, etc.) from the results directory.

## Suggestion

Could reuse the existing HTML report generation logic but run it against a results directory instead of requiring a live test run.