Self-host landing media and add safe Windows downloads

[masarray]

Summary

Completes the remaining landing-page hardening work by self-hosting product media, switching social previews to a 1200×630 PNG, and adding a release-aware Windows download workflow.

Local media

• Reuses the existing Git blobs for all six ARSAS screenshots under landing/assets/screenshots.
• GitHub Pages deploys HTML that references those local assets instead of raw.githubusercontent.com.
• Keeps the original screenshot files in Assets/screenshot as the README/source originals without recompressing them.
• Adds a 1200×630 PNG social card for more reliable Yammer, Viva Engage, LinkedIn, and other Open Graph previews.

Download workflow

• Adds download.html as the stable product CTA target.
• Queries the public GitHub latest-release API and activates direct installer or portable links only when matching assets exist.
• Never publishes an invented or broken installer URL.
• Falls back clearly to GitHub Releases and source-build instructions when no valid binary asset is available.
• Exposes checksum/release-file links when published.

Deployment architecture

• Adds a deterministic landing build step that copies landing/ into _site.
• Rewrites screenshot references, social-card metadata, JSON-LD downloadUrl, and website CTAs in the deployable static artifact.
• Preserves the source-build fallback on the download page.
• Adds a dedicated validator for local media, the 1200×630 PNG, release-aware download controls, and absence of remote screenshot URLs.
• GitHub Pages now uploads _site rather than the unbuilt source directory.

Validation

• Source landing HTML, links, metadata, JSON-LD, sitemap, and branding
• Deployable _site build with local screenshots
• 1200×630 PNG social preview validation
• Release-aware download controls and source-build fallback
• Public website and license boundaries
• UX, GOOSE, and SAS invariants
• ARIEC61850 compatibility gate
• .NET restore and Release build
• Portable Windows publish and artifact upload

Boundaries

• No ARSAS application or ARIEC61850 runtime code is changed.
• The download page does not claim that a release exists when GitHub cannot confirm one.
• Installer availability is derived from actual published release assets at page load.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Map each screenshot URL to its matching copied blob

The first three local screenshot files do not contain the screenshots their names and mappings claim: in this commit arsas-first-launch.webp is the original arsas (3).webp, arsas-multi-ied.webp is original (1), and arsas-live-values.webp is original (2). Consequently the deployed build replaces the source URL for screenshot 1 with screenshot 3 (and cyclically for 2/3), so the home hero and the affected captions/alt text describe the wrong product screens.

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