feat: create autonomous Nivora package repository

Maintain a validated cross-distribution package catalog.
Automate upstream updates, isolated builds, diagnostics, and direct publication.
Build the official GitHub Desktop sources for Linux with working OAuth.

happ/postremove.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+
+set -euo pipefail
+
+optional_refresh() {
+    local label=$1
+    shift
+
+    if ! "$@"; then
+        echo "Предупреждение: не удалось обновить ${label}." >&2
+    fi
+}
+
+unit=/usr/lib/systemd/system/happd.service
+if [[ ! -e "$unit" ]] && command -v systemctl >/dev/null 2>&1 && [[ -d /run/systemd/system ]]; then
+    if systemctl is-active --quiet happd.service; then
+        systemctl stop happd.service
+    fi
+    if systemctl is-enabled --quiet happd.service; then
+        systemctl disable happd.service
+    fi
+    systemctl daemon-reload
+fi
+
+# Обновляем MIME-базу данных
+if command -v update-mime-database &>/dev/null; then
+    optional_refresh "MIME-базу" update-mime-database /usr/share/mime
+fi
+
+# Обновляем desktop базу данных
+if command -v update-desktop-database &>/dev/null; then
+    optional_refresh "desktop-базу" update-desktop-database -q /usr/share/applications
+fi
+
+# Обновляем кэш иконок
+if command -v gtk-update-icon-cache &>/dev/null; then
+    optional_refresh "кэш иконок" gtk-update-icon-cache -f -q /usr/share/icons/hicolor
+fi