refactor: move pkg/ to internal/ and update imports

Restructure project by relocating package contents from pkg/ to internal/ to better reflect internal-only usage. This commit is initial step to prepare project for public api

internal/build/cache.go

@@ -0,0 +1,69 @@
+// ALR - Any Linux Repository
+// Copyright (C) 2025 The ALR Authors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package build
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+
+	"github.com/goreleaser/nfpm/v2"
+
+	"gitea.plemya-x.ru/Plemya-x/ALR/internal/types"
+)
+
+type Cache struct {
+	cfg Config
+}
+
+func (c *Cache) CheckForBuiltPackage(
+	ctx context.Context,
+	input *BuildInput,
+	vars *types.BuildVars,
+) (string, bool, error) {
+	filename, err := pkgFileName(input, vars)
+	if err != nil {
+		return "", false, err
+	}
+
+	pkgPath := filepath.Join(getBaseDir(c.cfg, vars.Name), filename)
+
+	_, err = os.Stat(pkgPath)
+	if err != nil {
+		return "", false, nil
+	}
+
+	return pkgPath, true, nil
+}
+
+func pkgFileName(
+	input interface {
+		OsInfoProvider
+		PkgFormatProvider
+		RepositoryProvider
+	},
+	vars *types.BuildVars,
+) (string, error) {
+	pkgInfo := getBasePkgInfo(vars, input)
+
+	packager, err := nfpm.Get(input.PkgFormat())
+	if err != nil {
+		return "", err
+	}
+
+	return packager.ConventionalFileName(pkgInfo), nil
+}