Add boot image management with ISO extraction and serving

Upload Proxmox ISOs via API or dashboard UI, extract kernel+initrd
using pure-Go iso9660 library, store on disk, and serve over HTTP
for PXE booting. Dynamic kernel/initrd filenames per image replace
the previous hardcoded paths.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/image/service.go

@@ -0,0 +1,87 @@
+package image
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"regexp"
+
+	"provisioning/internal/model"
+	"provisioning/internal/store"
+)
+
+type Service struct {
+	Store    *store.Images
+	ImageDir string
+}
+
+type UploadParams struct {
+	Name    string
+	Kind    string
+	Version string
+	ISO     io.Reader
+}
+
+var slugRegex = regexp.MustCompile(`^[a-z0-9][a-z0-9.-]*$`)
+
+func (s *Service) Upload(ctx context.Context, p UploadParams) (*model.Image, error) {
+	if !slugRegex.MatchString(p.Name) {
+		return nil, fmt.Errorf("invalid name %q: must be lowercase alphanumeric with hyphens/dots", p.Name)
+	}
+	if p.Kind == "" {
+		p.Kind = "proxmox"
+	}
+	if p.Version == "" {
+		return nil, fmt.Errorf("version is required")
+	}
+
+	if _, err := s.Store.GetByName(ctx, p.Name); err == nil {
+		return nil, fmt.Errorf("image %q already exists", p.Name)
+	}
+
+	destDir := filepath.Join(s.ImageDir, p.Name)
+	if err := os.MkdirAll(destDir, 0o755); err != nil {
+		return nil, fmt.Errorf("create image dir: %w", err)
+	}
+
+	result, err := ExtractFromISO(p.ISO, destDir)
+	if err != nil {
+		os.RemoveAll(destDir)
+		return nil, fmt.Errorf("extract ISO: %w", err)
+	}
+
+	kernelPath := filepath.Join(p.Name, result.KernelFilename)
+	initrdPath := filepath.Join(p.Name, result.InitrdFilename)
+
+	id, err := s.Store.Create(ctx, model.Image{
+		Name:       p.Name,
+		Kind:       p.Kind,
+		Version:    p.Version,
+		KernelPath: kernelPath,
+		InitrdPath: initrdPath,
+	})
+	if err != nil {
+		os.RemoveAll(destDir)
+		return nil, fmt.Errorf("save image record: %w", err)
+	}
+
+	img, err := s.Store.Get(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	return img, nil
+}
+
+func (s *Service) Delete(ctx context.Context, id int64) error {
+	img, err := s.Store.Get(ctx, id)
+	if err != nil {
+		return err
+	}
+
+	destDir := filepath.Join(s.ImageDir, img.Name)
+	os.RemoveAll(destDir)
+
+	return s.Store.Delete(ctx, id)
+}