Add build and run scripts; drop the broken Avalonia.Diagnostics reference

A wrapper around `dotnet build` earns nothing, so build.ps1/build.sh are the
full local gate instead — tool restore, package restore, format check, build,
test — in the order that fails cheapest first, with a non-zero exit on failure.
run.ps1/run.sh default to Debug and pass extra arguments through to the app.
Both flavours ship because the Desktop head targets Windows, Linux and macOS.

Writing them immediately paid for itself: the very first run failed restore on
Avalonia.Diagnostics 12.1.1, which does not exist — the package stops at 11.3.x
because Avalonia 12 moved the inspector into a separate tool with its own
installation. The reference had survived because it sat behind
Condition="'$(Configuration)' == 'Debug'", and `dotnet restore` evaluates with
the default configuration while every build so far had passed -c Release. So
`dotnet build -c Release` worked and a bare `dotnet restore` did not.

Reference removed rather than replaced: AvaloniaUI.DiagnosticsSupport pulls in a
separately installed tool, which is not a dependency to add to a skeleton without
asking. README and CLAUDE.md no longer promise F12, and both traps are written
down where the next person will hit them.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

build.sh

@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+# Полный локальный гейт: формат, сборка, тесты.
+#
+# Обёртка вокруг `dotnet build` сама по себе бесполезна — ценность в том, что шаги идут в
+# правильном порядке, падают быстро и возвращают ненулевой код возврата.
+#
+#   ./build.sh                  формат, сборка и тесты в Release
+#   ./build.sh --fix            переформатировать код, затем собрать и прогнать тесты
+#   ./build.sh -c Debug         другая конфигурация
+#   ./build.sh --skip-tests     только собрать
+
+set -euo pipefail
+cd "$(dirname "$0")"
+
+SOLUTION=AvParser.slnx
+CONFIGURATION=Release
+FIX=0
+SKIP_FORMAT=0
+SKIP_TESTS=0
+
+while [ $# -gt 0 ]; do
+    case "$1" in
+        -c|--configuration) CONFIGURATION="$2"; shift 2 ;;
+        --fix)              FIX=1;         shift ;;
+        --skip-format)      SKIP_FORMAT=1; shift ;;
+        --skip-tests)       SKIP_TESTS=1;  shift ;;
+        -h|--help)          sed -n '2,10p' "$0"; exit 0 ;;
+        *) echo "Неизвестный аргумент: $1" >&2; exit 2 ;;
+    esac
+done
+
+case "$CONFIGURATION" in
+    Debug|Release) ;;
+    *) echo "Конфигурация должна быть Debug или Release, получено: $CONFIGURATION" >&2; exit 2 ;;
+esac
+
+step() { printf '\n\033[36m==> %s\033[0m\n' "$1"; }
+
+trap 'printf "\n\033[31mСБОЙ на шаге: %s\033[0m\n" "${CURRENT_STEP:-?}" >&2' ERR
+
+CURRENT_STEP='Локальные инструменты'; step "$CURRENT_STEP"
+dotnet tool restore
+
+CURRENT_STEP='Восстановление пакетов'; step "$CURRENT_STEP"
+dotnet restore "$SOLUTION"
+
+if [ "$SKIP_FORMAT" -eq 0 ]; then
+    if [ "$FIX" -eq 1 ]; then
+        CURRENT_STEP='Форматирование (csharpier format)'; step "$CURRENT_STEP"
+        dotnet csharpier format .
+    else
+        # До сборки: несформатированный файл — самый дешёвый повод упасть.
+        CURRENT_STEP='Проверка форматирования (csharpier check)'; step "$CURRENT_STEP"
+        dotnet csharpier check .
+    fi
+fi
+
+CURRENT_STEP="Сборка ($CONFIGURATION)"; step "$CURRENT_STEP"
+dotnet build "$SOLUTION" -c "$CONFIGURATION" --no-restore --nologo
+
+if [ "$SKIP_TESTS" -eq 0 ]; then
+    CURRENT_STEP='Тесты'; step "$CURRENT_STEP"
+    dotnet test "$SOLUTION" -c "$CONFIGURATION" --no-build --nologo
+fi
+
+printf '\n\033[32mOK\033[0m\n'