docs: add user-friendly Furo documentation site

[kiro-agent]

This pull request was created by @kiro-agent on behalf of @weebzone 👻

Comment with /kiro fix to address specific feedback or /kiro all to address everything.
_{Learn about Kiro Web}

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Summary

Adds a complete, beginner-friendly documentation site under docs/, built with Sphinx + the Furo theme and written in MyST Markdown. Content is split into multiple navigable pages (like FastAPI/Docker docs) instead of one giant README, and written in layman's terms with Beginner Tip / Common Mistake / Recommended / Good to Know callout boxes throughout.

All content is derived from a full scan of the codebase, so it accurately reflects real behavior (filename parsing, split/combined files, manual entry, auto-catalog rules, config variables, streaming, API endpoints, themes, deployment).

Pages included

• Get Started: Home, Getting Started, Configuration
• Using the App: Streaming, Media Management, Catalogs, Search, User Management, Admin Panel, Themes
• Reference & Ops: API Reference, Deployment, Updating/Backup
• Help: Troubleshooting, FAQ, Tips & Best Practices
• Project: Contributing, Changelog, Credits, License, Support

Notable accurate details documented

• Filename parsing pipeline (cleaning + PTN/GuessIt), the hard requirement of title + resolution, and movie-vs-TV logic.
• Split files (.ext.NN) grouping and combined-episode / season-pack handling.
• Manual entry via public/private Telegram links and quality-from-video-height.
• Auto-catalog groups (Language / Smart / OTT) and the TMDB-key requirement.
• Full config split: config.env startup vars vs. runtime web-panel settings.
• Stremio + streaming endpoints and how the proxy URL is prepended.
• 13 themes, deployment options (Docker, Compose, VPS+Caddy, Hugging Face, Heroku).

How it was tested

• Built locally with sphinx-build -b html -W --keep-going (warnings treated as errors) — build succeeds with zero warnings.
• Build artifacts (_build/) and the local .venv/ are git-ignored.

How to build/preview

cd docs
pip install -r requirements.txt
sphinx-build -b html . _build/html
# open docs/_build/html/index.html

Notes / follow-ups

• The Changelog page summarizes current capabilities and points to GitHub Releases as the source of truth (the repo has no structured CHANGELOG file yet).
• Screenshots/GIFs and an architecture image were intentionally left as text diagrams; real screenshots can be dropped into docs/_static/ later.
• Optional next step: a CI workflow (or Read the Docs / GitHub Pages) to publish the site automatically.