Web UI for mvsMF management console

[mgrossmann]

Add a browser-based web UI for mvsMF that provides a modern management console for MVS 3.8j.

Scope

• Design system ("The Sovereign Console") — documented in doc/DESIGN.md
• HTML pages: Dashboard, Datasets, Files (USS), Spool viewer, Login, API Docs, Trace viewer
• CSS/JS: Custom stylesheet and application logic (web/css/style.css, web/js/app.js, web/js/auth.js)
• All pages consume the existing mvsMF REST API (/zosmf/restfiles/, /zosmf/restjobs/)

Files

doc/DESIGN.md          — Design system document
web/index.html         — Main entry / navigation
web/login.html         — Login page
web/dashboard.html     — System dashboard
web/datasets.html      — Dataset explorer
web/files.html         — USS file explorer
web/spool.html         — JES spool viewer
web/docs.html          — API documentation
web/trace.html         — HTTP trace viewer
web/css/style.css      — Stylesheet
web/js/app.js          — Application logic
web/js/auth.js         — Authentication handling