feat(desktop): add artifacts explorer v1 to QuantLab shell

[Whiteks1]

Summary

Add a focused native Artifacts Explorer to QuantLab Desktop for reports, configs, logs, and machine-readable outputs.

Why

Artifacts are central to auditability and reproducibility.
The current shell can open artifacts, but it still needs a clearer native explorer that makes outputs easier to navigate and inspect.

Scope

This issue should cover:

• a native artifacts surface for a selected run or launch job
• grouped access to canonical report, config, logs, and manifest entries
• clearer distinction between run artifacts and launch-job logs
• honest empty and missing-file states

Non-goals

Do not:

• add artifact editing
• add indexing across the entire repo
• add semantic search or AI recommendations
• redesign the whole shell around this surface

Implementation Notes

Data sources:

• run artifact manifests and canonical report files under outputs/runs/...
• launch-job stdout and stderr paths already exposed by launch-control

Reusable state and UI:

• extend the current shell-native artifacts and job-review tabs
• do not replace the browser path unless the native path is clearly better for that artifact class

Expected files to touch:

• desktop/main.js or desktop/preload.js only if extra read helpers are needed
• desktop/renderer/app.js
• desktop/renderer/index.html
• desktop/renderer/styles.css

Minimal UI contract:

• separate run artifacts from launch-job logs
• display file name, type, and lightweight metadata when available
• keep a clear backlink to the owning run or launch job
• missing files must render as missing, not just silently disappear

Acceptance Criteria

• the operator can inspect run and job artifacts without dropping into raw file browsing
• missing artifacts are shown clearly instead of failing silently
• artifacts remain linked back to the owning run or launch job