Wire up image handler endpoint with service orchestration

- Add image proxy config options (signing_key, whitelist_hosts, allow_http)
- Create Service to orchestrate cache, fetcher, and processor
- Initialize image service in handlers OnStart hook
- Implement HandleImage with URL parsing, signature validation, cache
- Implement HandleRobotsTxt for search engine prevention
- Parse query params for signature, quality, and fit mode

internal/config/config.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"git.eeqj.de/sneak/smartconfig"
 	"go.uber.org/fx"
@@ -35,6 +36,11 @@ type Config struct {
 	SentryDSN       string
 	StateDir        string
 	DBURL           string
+
+	// Image proxy settings
+	SigningKey     string   // HMAC signing key for URL signatures
+	WhitelistHosts []string // Hosts that don't require signatures
+	AllowHTTP      bool     // Allow non-TLS upstream (testing only)
 }
 
 // New creates a new Config instance by loading configuration from file.
@@ -79,6 +85,9 @@ func New(_ fx.Lifecycle, params Params) (*Config, error) {
 		SentryDSN:       getString(sc, "sentry_dsn", ""),
 		MetricsUsername: getString(sc, "metrics.username", ""),
 		MetricsPassword: getString(sc, "metrics.password", ""),
+		SigningKey:      getString(sc, "signing_key", ""),
+		WhitelistHosts:  getStringSlice(sc, "whitelist_hosts"),
+		AllowHTTP:       getBool(sc, "allow_http", false),
 	}
 
 	// Build DBURL from StateDir if not explicitly set
@@ -132,3 +141,27 @@ func getBool(sc *smartconfig.Config, key string, defaultVal bool) bool {
 
 	return val
 }
+
+func getStringSlice(sc *smartconfig.Config, key string) []string {
+	if sc == nil {
+		return nil
+	}
+
+	val, err := sc.GetString(key)
+	if err != nil || val == "" {
+		return nil
+	}
+
+	// Parse comma-separated values
+	parts := strings.Split(val, ",")
+	result := make([]string, 0, len(parts))
+
+	for _, part := range parts {
+		trimmed := strings.TrimSpace(part)
+		if trimmed != "" {
+			result = append(result, trimmed)
+		}
+	}
+
+	return result
+}