Add archive relay query augmentation and access-based GC (v0.45.0)

- Add async archive relay querying (local results immediate, archives in background)
- Add query caching with filter normalization to avoid repeated requests
- Add session-deduplicated access tracking for events
- Add continuous garbage collection based on access patterns
- Auto-detect storage limit (80% of filesystem) when ORLY_MAX_STORAGE_BYTES=0
- Support NIP-50 search queries to archive relays

New environment variables:
- ORLY_ARCHIVE_ENABLED: Enable archive relay query augmentation
- ORLY_ARCHIVE_RELAYS: Comma-separated archive relay URLs
- ORLY_ARCHIVE_TIMEOUT_SEC: Archive query timeout
- ORLY_ARCHIVE_CACHE_TTL_HRS: Query deduplication window
- ORLY_GC_ENABLED: Enable access-based garbage collection
- ORLY_MAX_STORAGE_BYTES: Max storage (0=auto 80%)
- ORLY_GC_INTERVAL_SEC: GC check interval
- ORLY_GC_BATCH_SIZE: Events per GC cycle

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pkg/storage/limits_windows.go

@@ -0,0 +1,38 @@
+//go:build windows
+
+package storage
+
+import (
+	"errors"
+)
+
+// FilesystemStats holds information about filesystem space usage.
+type FilesystemStats struct {
+	Total     uint64 // Total bytes on filesystem
+	Available uint64 // Available bytes (for unprivileged users)
+	Used      uint64 // Used bytes
+}
+
+// GetFilesystemStats returns filesystem space information for the given path.
+// Windows implementation is not yet supported.
+func GetFilesystemStats(path string) (stats FilesystemStats, err error) {
+	// TODO: Implement using syscall.GetDiskFreeSpaceEx
+	err = errors.New("filesystem stats not implemented on Windows")
+	return
+}
+
+// CalculateMaxStorage calculates the maximum storage limit for the relay.
+// If configuredMax > 0, it returns that value directly.
+// Windows auto-detection is not yet supported.
+func CalculateMaxStorage(dataDir string, configuredMax int64) (int64, error) {
+	if configuredMax > 0 {
+		return configuredMax, nil
+	}
+	return 0, errors.New("auto-detect storage limit not implemented on Windows; set ORLY_MAX_STORAGE_BYTES manually")
+}
+
+// GetCurrentStorageUsage calculates the current storage usage of the data directory.
+// Windows implementation is not yet supported.
+func GetCurrentStorageUsage(dataDir string) (int64, error) {
+	return 0, errors.New("storage usage detection not implemented on Windows")
+}