feat: add upload policies, daily limits, and storage quotas

- Add environment variables to configure anonymous uploads, daily upload caps, and default user storage limits.
- Update config loader to parse and validate the new settings.
- Implement backend logic to track daily usage and active storage per user.
- Update README and `.env.example` to document the new settings and admin panels.

backend/libs/services/settings_test.go

@@ -0,0 +1,173 @@
+package services
+
+import (
+	"log/slog"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"warpbox.dev/backend/libs/config"
+)
+
+func TestSettingsLoadDefaultsAndOverrides(t *testing.T) {
+	settings := newTestSettingsService(t)
+	policy, err := settings.UploadPolicy()
+	if err != nil {
+		t.Fatalf("UploadPolicy returned error: %v", err)
+	}
+	if !policy.AnonymousUploadsEnabled || policy.AnonymousMaxUploadMB != 512 {
+		t.Fatalf("default policy = %+v", policy)
+	}
+
+	policy.AnonymousUploadsEnabled = false
+	policy.UserDailyUploadMB = 123
+	if err := settings.UpdateUploadPolicy(policy); err != nil {
+		t.Fatalf("UpdateUploadPolicy returned error: %v", err)
+	}
+	next, err := settings.UploadPolicy()
+	if err != nil {
+		t.Fatalf("UploadPolicy returned error: %v", err)
+	}
+	if next.AnonymousUploadsEnabled || next.UserDailyUploadMB != 123 {
+		t.Fatalf("override policy = %+v", next)
+	}
+}
+
+func TestSettingsUseNewEnvDefaultsUntilSaved(t *testing.T) {
+	root := t.TempDir()
+	upload, err := NewUploadService(1024*1024, filepath.Join(root, "data"), "http://example.test", slog.Default())
+	if err != nil {
+		t.Fatalf("NewUploadService returned error: %v", err)
+	}
+	defer upload.Close()
+
+	first, err := NewSettingsService(upload.DB(), config.SettingsDefaults{
+		AnonymousUploadsEnabled: true,
+		AnonymousMaxUploadMB:    111,
+		AnonymousDailyUploadMB:  222,
+		UserDailyUploadMB:       333,
+		DefaultUserStorageMB:    444,
+		UsageRetentionDays:      30,
+	})
+	if err != nil {
+		t.Fatalf("NewSettingsService first returned error: %v", err)
+	}
+	firstPolicy, err := first.UploadPolicy()
+	if err != nil {
+		t.Fatalf("UploadPolicy first returned error: %v", err)
+	}
+	if firstPolicy.AnonymousMaxUploadMB != 111 {
+		t.Fatalf("first AnonymousMaxUploadMB = %v, want 111", firstPolicy.AnonymousMaxUploadMB)
+	}
+
+	second, err := NewSettingsService(upload.DB(), config.SettingsDefaults{
+		AnonymousUploadsEnabled: true,
+		AnonymousMaxUploadMB:    555,
+		AnonymousDailyUploadMB:  666,
+		UserDailyUploadMB:       777,
+		DefaultUserStorageMB:    888,
+		UsageRetentionDays:      30,
+	})
+	if err != nil {
+		t.Fatalf("NewSettingsService second returned error: %v", err)
+	}
+	secondPolicy, err := second.UploadPolicy()
+	if err != nil {
+		t.Fatalf("UploadPolicy second returned error: %v", err)
+	}
+	if secondPolicy.AnonymousMaxUploadMB != 555 {
+		t.Fatalf("second AnonymousMaxUploadMB = %v, want 555", secondPolicy.AnonymousMaxUploadMB)
+	}
+
+	if err := second.UpdateUploadPolicy(secondPolicy); err != nil {
+		t.Fatalf("UpdateUploadPolicy returned error: %v", err)
+	}
+	third, err := NewSettingsService(upload.DB(), config.SettingsDefaults{
+		AnonymousUploadsEnabled: true,
+		AnonymousMaxUploadMB:    999,
+		AnonymousDailyUploadMB:  999,
+		UserDailyUploadMB:       999,
+		DefaultUserStorageMB:    999,
+		UsageRetentionDays:      30,
+	})
+	if err != nil {
+		t.Fatalf("NewSettingsService third returned error: %v", err)
+	}
+	thirdPolicy, err := third.UploadPolicy()
+	if err != nil {
+		t.Fatalf("UploadPolicy third returned error: %v", err)
+	}
+	if thirdPolicy.AnonymousMaxUploadMB != 555 {
+		t.Fatalf("third AnonymousMaxUploadMB = %v, want persisted 555", thirdPolicy.AnonymousMaxUploadMB)
+	}
+}
+
+func TestSettingsRejectInvalidMegabytes(t *testing.T) {
+	if _, err := ParseMegabytesValue("0"); err == nil {
+		t.Fatalf("ParseMegabytesValue accepted zero")
+	}
+	settings := newTestSettingsService(t)
+	policy, err := settings.UploadPolicy()
+	if err != nil {
+		t.Fatalf("UploadPolicy returned error: %v", err)
+	}
+	policy.DefaultUserStorageMB = -1
+	if err := settings.UpdateUploadPolicy(policy); err == nil {
+		t.Fatalf("UpdateUploadPolicy accepted negative storage")
+	}
+}
+
+func TestDailyUsageAndCleanup(t *testing.T) {
+	settings := newTestSettingsService(t)
+	now := time.Date(2026, 5, 30, 12, 0, 0, 0, time.UTC)
+	if err := settings.AddUsage("ip", "127.0.0.1", 1024, now); err != nil {
+		t.Fatalf("AddUsage returned error: %v", err)
+	}
+	if err := settings.AddUsage("ip", "127.0.0.1", 2048, now); err != nil {
+		t.Fatalf("AddUsage returned error: %v", err)
+	}
+	usage, err := settings.UsageForIP("127.0.0.1", now)
+	if err != nil {
+		t.Fatalf("UsageForIP returned error: %v", err)
+	}
+	if usage.UploadedBytes != 3072 {
+		t.Fatalf("UploadedBytes = %d, want 3072", usage.UploadedBytes)
+	}
+
+	if err := settings.CleanupUsage(now.AddDate(0, 0, 31), 30); err != nil {
+		t.Fatalf("CleanupUsage returned error: %v", err)
+	}
+	usage, err = settings.UsageForIP("127.0.0.1", now)
+	if err != nil {
+		t.Fatalf("UsageForIP returned error: %v", err)
+	}
+	if usage.UploadedBytes != 0 {
+		t.Fatalf("UploadedBytes after cleanup = %d, want 0", usage.UploadedBytes)
+	}
+}
+
+func newTestSettingsService(t *testing.T) *SettingsService {
+	t.Helper()
+	root := t.TempDir()
+	upload, err := NewUploadService(1024*1024, filepath.Join(root, "data"), "http://example.test", slog.Default())
+	if err != nil {
+		t.Fatalf("NewUploadService returned error: %v", err)
+	}
+	t.Cleanup(func() {
+		if err := upload.Close(); err != nil {
+			t.Fatalf("Close returned error: %v", err)
+		}
+	})
+	settings, err := NewSettingsService(upload.DB(), config.SettingsDefaults{
+		AnonymousUploadsEnabled: true,
+		AnonymousMaxUploadMB:    512,
+		AnonymousDailyUploadMB:  2048,
+		UserDailyUploadMB:       8192,
+		DefaultUserStorageMB:    51200,
+		UsageRetentionDays:      30,
+	})
+	if err != nil {
+		t.Fatalf("NewSettingsService returned error: %v", err)
+	}
+	return settings
+}