Add rack image and SC diagram SVG

- Added a new image file for the rack located at feature/rack/rack.png.
- Introduced a new SVG file for the SC diagram at now/phys/sc-diagram.drawio.svg, containing detailed graphical representations of network components and their connections.

.gitattributes

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+# Treat most files as auto-detected text (normalizes CRLF/LF when core.autocrlf is used)
+* text=auto
+
+# Explicit binary files (don't attempt CRLF normalization or textual diffs)
+*.png binary
+*.jpg binary
+*.jpeg binary
+*.gif binary
+*.ico binary
+*.fbx binary
+*.blend binary
+*.blend1 binary
+*.zip binary
+*.tar.gz binary
+*.7z binary
+*.exe binary
+*.dll binary
+
+# SVGs are XML/text — keep text diffs
+*.svg text diff=svg
+
+# Markdown: keep LF endings for consistent diffs across platforms
+*.md text eol=lf
+
+# PowerShell scripts: prefer CRLF on Windows authors
+*.ps1 text eol=crlf