Make nilmtk.github.io the canonical ecosystem guide

[nipunbatra]

Outcome

Replaces the stale 2015 landing page with the canonical router for the modern NILMTK ecosystem. A new user can now answer four questions immediately:

1. Which repository should I use?
2. What is the supported installation path?
3. When should I use Docker?
4. Which papers should I cite?

What changed

• gives NILMTK core, NILM Metadata, nilmtk-contrib, and NILMbench one explicit responsibility each
• explains the data-to-metadata-to-model-to-benchmark architecture
• provides copyable Python 3.11 and uv instructions for core, models, and NILMbench
• documents one general contrib Dockerfile plus separate CPU/CUDA scientific runtimes owned by NILMbench; no per-model images
• adds a citation decision table for the 2014 core, 2014 metadata, 2019 contrib, and 2026 benchmark papers
• shows the auditable route from a model PR to a real-data leaderboard result
• removes Bootstrap 3, jQuery 1.10, insecure font URLs, obsolete v0.2 claims, malformed HTML, and retired navigation
• adds semantic responsive HTML, keyboard-accessible tabs/menu, reduced-motion support, a favicon, exact local preview instructions, and dependency-free CI checks
• leaves the generated core API documentation under nilmtk/ untouched

Verification

• python3 scripts/check_site.py: passed; 22 IDs, 46 links/assets, 9 canonical URLs
• node --check js/site.js: passed
• git diff --check: passed
• canonical repository, API documentation, benchmark, and DOI links: HTTP 200 or expected DOI 302
• desktop 1440×1100 and mobile 390×844 full-page screenshots inspected
• Playwright: no horizontal overflow at either viewport; tabs, mobile menu, Escape handling, and ARIA state passed; no browser console errors

Docker release note

The existing GHCR package returns 403 to an anonymous pull because its package visibility is private. This page therefore publishes the working local-build route instead of a broken pull command. Once the organization deliberately makes that package public, a small follow-up can switch the Docker tab to ghcr.io/nilmtk/nilmtk-contrib:latest.