me-web? skeleton: Avalonia 12 app, server, packaging and CI

The first screen (online or not, a Check button, every language with a
draft notice), the desktop and Android heads, the server's /api/info and
/api/ip, a release tool that builds deb, rpm, a Windows exe, macOS zips,
a signed APK and the server, and the Gitea workflows that run it. Rules
adapted from passolo; AGPL-3.0.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

tools/sdk.sh

@@ -0,0 +1,16 @@
+root="$(cd "$(dirname "$0")/.." && pwd)"
+sdk=$(sed -n 's/.*"version": *"\([^"]*\)".*/\1/p' "$root/global.json" | head -n 1)
+has_sdk() { [ -x "$1/dotnet" ] && [ -w "$1" ] && (cd "$root" && "$1/dotnet" --version >/dev/null 2>&1); }
+dotnet_dir=""
+for candidate in "$DOTNET_ROOT" "$HOME/.dotnet"; do
+  if [ -n "$candidate" ] && has_sdk "$candidate"; then dotnet_dir="$candidate"; break; fi
+done
+if [ -z "$dotnet_dir" ]; then
+  dotnet_dir="$HOME/.dotnet"
+  echo ".NET SDK $sdk not found: installing it into $dotnet_dir"
+  script="${TMPDIR:-/tmp}/dotnet-install.sh"
+  curl -fsSL https://dot.net/v1/dotnet-install.sh -o "$script"
+  bash "$script" --version "$sdk" --install-dir "$dotnet_dir"
+fi
+export DOTNET_ROOT="$dotnet_dir" PATH="$dotnet_dir:$PATH" DOTNET_CLI_TELEMETRY_OPTOUT=1 DOTNET_NOLOGO=1
+cd "$root"