VOD unlocker Save-As download (#51) + README redesign

[Soulhackzlol]

Summary

Two things on one branch: the fix for the open VOD-unlocker download bug (#51), and a full README redesign.

fix: VOD unlocker downloads where the user chooses (Closes #51)

The downloader wrote the script to a fixed %APPDATA%\obs-studio\scripts path, which silently missed portable and non-standard OBS installs (the root cause reported in #51). Now:

• The Lua script is embedded (include_str!) and served at GET /obs/vod-script/download with a Content-Disposition attachment.
• The dashboard uses the File System Access API (showSaveFilePicker) so the user picks the folder, with a plain-download fallback on browsers without it.
• No network round-trip and no release-asset version skew: it always matches the running binary.
• Removed the now-dead install_vod_script, obs_scripts_dir, vod_script_installed, self_update::download_latest_asset, the POST /obs/vod-script/install route, and the vod_script_installed field on /obs/register-status.
• The legacy OBS quick launch (Enhanced Broadcasting via --config-url) now collapses into an expandable section on OBS 32.2+, where OBS ignores that flag for custom services.

docs: README redesign (EN + ES)

• Benefit-first structure (Quickstart, Why, Features, then How it works); deep internals folded into collapsed sections.
• New benefit-card hero (docs/pipeline.svg) and a rebuilt, smoothed 3-step Arm/Activate/Cut graphic (docs/states.svg).
• A Download for Windows CTA and a SmartScreen reassurance note near the top, plus a privacy line (keys never leave your PC, no telemetry).
• FAQ answered from the app's actual behavior.
• SEO pass: multistream / simulcast and the free Restream + InstantDelay alternative framing, a Spanish "delay" synonym, and <kbd> to <code> accessibility fixes on states/ports.
• Dropped the stale binary-size mentions; added the project icon assets.

Testing

• cargo build --release and cargo clippy --all-targets -- -D warnings clean; 282 tests green.
• Verified live against a running binary: GET /obs/vod-script/download returns the byte-identical script with the attachment header, showSaveFilePicker is present in the served HTML, and the old POST /obs/vod-script/install route 404s.

Notes

• The fix reaches users at the next release cut. The code no longer needs the release asset, but users still need a build that contains this change.