UI/UX: Replace the light-only interface with a dark theme

Summary

MobSF's current web UI is light-themed only. For a tool that's used for long analysis sessions — reading manifests, scrolling through permission/API tables, watching dynamic-analysis logs, comparing scan reports — a bright white interface gets uncomfortable quickly, especially compared to the dark-by-default tooling most of this audience already uses daily (Burp Suite, Android Studio, browser DevTools, terminal-based tools).

Proposal

Redesign the web UI around a dark theme as the default look:

• A single, consistent dark color system (backgrounds, borders, text, accent colors) applied across the shared layout (navbar, sidebar, footer), cards, tables, forms, modals, and buttons, rather than page-by-page overrides.
• Keep the existing AdminLTE/Bootstrap structure and functionality untouched — this is a visual/theming change, not a rework of behavior.
• Carry the theme through every page: dashboard, recent scans, static/dynamic analysis reports, auth pages (login/register/change password), and error pages (403/404/500).

Motivation

• Reduced eye strain during long analysis sessions.
• Visual consistency with the security-tooling ecosystem MobSF's users already work in.
• Modernizes the interface without changing any existing functionality or workflow.

I have a working implementation of this and will follow up with a PR.