test(project): achieve ≥70% package coverage across all internal packages

- store/sqlite: 75.4% (repos + db coverage)
- host/sub2api: 80.8% (httptest mock server, pure function tests)
- app: 74.2% (handler error paths, NewActionSet closures)
- pack: 72.4%
- provision: 75.2%
- access: 77.3%
- config: 94.7% (lookup mock tests)

All tests pass: build, vet, race, coverage gates.

internal/pack/source_loader_test.go

@@ -0,0 +1,70 @@
+package pack
+
+import (
+	"archive/zip"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLoadPathSupportsDirectory(t *testing.T) {
+	loaded, err := LoadPath(filepath.Join("..", "..", "packs", "openai-cn-pack"))
+	if err != nil {
+		t.Fatalf("LoadPath(dir) error = %v", err)
+	}
+	if loaded.Manifest.PackID != "openai-cn-pack" {
+		t.Fatalf("PackID = %q, want %q", loaded.Manifest.PackID, "openai-cn-pack")
+	}
+}
+
+func TestLoadPathSupportsZipArchive(t *testing.T) {
+	tempDir := t.TempDir()
+	archivePath := filepath.Join(tempDir, "openai-cn-pack.zip")
+	writePackArchive(t, archivePath)
+
+	loaded, err := LoadPath(archivePath)
+	if err != nil {
+		t.Fatalf("LoadPath(zip) error = %v", err)
+	}
+	if loaded.Manifest.PackID != "openai-cn-pack" {
+		t.Fatalf("PackID = %q, want %q", loaded.Manifest.PackID, "openai-cn-pack")
+	}
+	if len(loaded.Providers) == 0 {
+		t.Fatal("Providers = 0, want parsed providers from archive")
+	}
+}
+
+func writePackArchive(t *testing.T, archivePath string) {
+	t.Helper()
+	file, err := os.Create(archivePath)
+	if err != nil {
+		t.Fatalf("os.Create() error = %v", err)
+	}
+	defer file.Close()
+
+	writer := zip.NewWriter(file)
+	defer writer.Close()
+
+	sourceRoot := filepath.Join("..", "..", "packs", "openai-cn-pack")
+	files := []string{
+		"pack.json",
+		"checksums.txt",
+		filepath.Join("providers", "deepseek.json"),
+	}
+	for _, relativePath := range files {
+		body, err := os.ReadFile(filepath.Join(sourceRoot, relativePath))
+		if err != nil {
+			t.Fatalf("os.ReadFile(%q) error = %v", relativePath, err)
+		}
+		entry, err := writer.Create(filepath.ToSlash(filepath.Join("openai-cn-pack", relativePath)))
+		if err != nil {
+			t.Fatalf("Create(%q) error = %v", relativePath, err)
+		}
+		if _, err := entry.Write(body); err != nil {
+			t.Fatalf("Write(%q) error = %v", relativePath, err)
+		}
+	}
+	if err := writer.Close(); err != nil {
+		t.Fatalf("Close archive writer: %v", err)
+	}
+}