Make README operating-system icons safe for GitHub iOS rendering

[cuberhaus]

Problem

The GitHub iOS app can fail with a generic "Algo salió mal" error when rendering the README's operating-system lists. The affected markup combines a remote SVG reference definition with reference-style images and escaped underscores in alt text, exercising a fragile native Markdown rendering path.

Scope

• Replace the Supported OS and WIP list icons with ordinary direct <img> elements referencing repository-owned PNG assets.
• Store small optimized PNG icons under a descriptive .github/assets/ subdirectory rather than depending on remote SVG or Imgur URLs.
• Use plain accessible alt text such as Arch, Manjaro, Ubuntu, macOS, and Gentoo; do not escape underscores in image alt text.
• Remove the obsolete reference-style image usages and definitions for these icons.
• Preserve the surrounding Supported OS, Window Managers, and WIP content unless it is factually stale.
• Keep icon dimensions explicit and visually consistent on GitHub web and mobile.

Acceptance criteria

• README contains no remote SVG image reference for the operating-system lists.
• The relevant icons use direct local PNG paths and no reference-style image syntax.
• make check or the repository's focused Markdown validation passes.
• GitHub web renders every icon and list correctly in light and dark themes.
• The repository opens successfully in the GitHub iOS app and the README reaches the affected sections without a renderer error.
• If iOS verification cannot be automated, record the app version and manual verification result in the pull request.

[cuberhaus]

Progress update: Supported OS and WIP icons now use small repository-owned direct PNGs with explicit dimensions and plain alt text; remote reference-style dependencies were removed. Focused Markdown lint passes.

[cuberhaus]

Status: In progress

Completed: Created isolated branch work/issues-13-47-71 from the current remote main baseline for the consolidated repository PR covering #13, #47, #71.
Blocker / remaining work: Transfer the verified repository batch, run required validation, commit, push, and open one linked PR. Individual issues with manual or unavailable-environment acceptance checks will remain open.

[cuberhaus]

Diagnosis update: the repository-specific Markdown hypothesis is falsified. On the App Store GitHub Mobile build, with cuberhaus selected, every tested repository shows "Algo salió mal", while the same public repository opens normally in iPhone Safari. Public README API requests return HTTP 200, the affected set spans public and private repositories, and GitHub Status is operational. This matches GitHub Community reports #160810 and #166676 for an app-wide iOS client failure. No further repository-content changes are justified; use Safari as the workaround and troubleshoot the Mobile app session/network path. This issue remains open only to record the eventual app-side resolution.

[cuberhaus]

Upstream report filed: https://github.com/orgs/community/discussions/206379. It includes the iPhone 15 / iOS 26.6.1 / GitHub Mobile 1.274.0 environment, Wi-Fi and cellular reproduction, full reinstall and reauthentication attempts, Safari success, REST/GraphQL success, and the public/private cross-repository scope. Further diagnosis now belongs in that Mobile discussion rather than repository README changes.