feat: progressive comment updates

[yoavf]

Proressively update the comment - from the moment the action starts taking screenshots until it ends

[Copilot]

Pull Request Overview

This PR implements progressive comment updates for screenshot capture, allowing real-time progress feedback in PR comments instead of waiting for all screenshots to complete.

• Splits comment posting into initial comment creation and progressive updates
• Adds progress callback to screenshot capture for incremental uploads and comment updates
• Refactors comment posting functions to support status tracking and real-time updates

Reviewed Changes

Copilot reviewed 3 out of 5 changed files in this pull request and generated 1 comment.

File	Description
src/screenshot-capture.ts	Adds onProgress callback option to CaptureOptions interface and invokes it after each screenshot
src/index.ts	Implements progressive screenshot capture with initial comment posting and incremental updates
src/comment-poster.ts	Refactors comment posting into separate initial and update functions with status tracking

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