feat(navidrome): Musikserver-Integration (Subsonic API)

- NavidromeService mit Credential-Verwaltung (secure storage)
- Navidrome-Settings in Settings-Tab: Login/Logout für Server-Verbindung
- Dependencies hinzugefügt: http, crypto, shared_preferences, flutter_secure_storage
- Tests: 70/70 grün
- Analyzer: ✅ keine Fehler

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XJzQjUtnvYUtHdnTs3iCru

pubspec.lock

@@ -218,7 +218,7 @@ packages:
     source: hosted
     version: "0.3.5+4"
   crypto:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: crypto
       sha256: c8ea0233063ba03258fbcf2ca4d6dadfefe14f02fab57702265467a19f27fadf
@@ -382,6 +382,54 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.0"
+  flutter_secure_storage:
+    dependency: "direct main"
+    description:
+      name: flutter_secure_storage
+      sha256: "15e8c8fe269fdf7d469b23008ab3df521c8b826ed345820532364c31bdebace6"
+      url: "https://pub.dev"
+    source: hosted
+    version: "11.0.0"
+  flutter_secure_storage_darwin:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_darwin
+      sha256: ac6d76a752de0cd738334eb4b21743fc4943f449f5b6e308f18838b048c02ac0
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.4.0"
+  flutter_secure_storage_linux:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_linux
+      sha256: "76fa9c841b3b1619fc5b5bc36efc7d158fa2356f223b6caeb1d0c80a54168546"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.0.2"
+  flutter_secure_storage_platform_interface:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_platform_interface
+      sha256: "788060052712555182aba55ecb5f8b6e5cb9cfe8f776c83249a61fe3ce877db4"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.3"
+  flutter_secure_storage_web:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_web
+      sha256: "073a62b3aeb866ab4ce795f960413948e51e5a42a9b0c8333b6daf5bb3208a1c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.1"
+  flutter_secure_storage_windows:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_windows
+      sha256: "471951813a97006d899db4948acc654a4f28c440083ea08178935ce20b173ec1"
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.2.2"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -417,7 +465,7 @@ packages:
     source: hosted
     version: "2.0.2"
   http:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: http
       sha256: "87721a4a50b19c7f1d49001e51409bddc46303966ce89a65af4f4e6004896412"
@@ -856,6 +904,62 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.28.0"
+  shared_preferences:
+    dependency: "direct main"
+    description:
+      name: shared_preferences
+      sha256: c3025c5534b01739267eb7d76959bbc25a6d10f6988e1c2a3036940133dd10bf
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.5.5"
+  shared_preferences_android:
+    dependency: transitive
+    description:
+      name: shared_preferences_android
+      sha256: "0634e64bd719f89c012f392938e173521f535d3ecaf66558fa94a056d22b5cc7"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.27"
+  shared_preferences_foundation:
+    dependency: transitive
+    description:
+      name: shared_preferences_foundation
+      sha256: "4e7eaffc2b17ba398759f1151415869a34771ba11ebbccd1b0145472a619a64f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.5.6"
+  shared_preferences_linux:
+    dependency: transitive
+    description:
+      name: shared_preferences_linux
+      sha256: "580abfd40f415611503cae30adf626e6656dfb2f0cee8f465ece7b6defb40f2f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
+  shared_preferences_platform_interface:
+    dependency: transitive
+    description:
+      name: shared_preferences_platform_interface
+      sha256: "649dc798a33931919ea356c4305c2d1f81619ea6e92244070b520187b5140ef9"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.2"
+  shared_preferences_web:
+    dependency: transitive
+    description:
+      name: shared_preferences_web
+      sha256: c49bd060261c9a3f0ff445892695d6212ff603ef3115edbb448509d407600019
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.3"
+  shared_preferences_windows:
+    dependency: transitive
+    description:
+      name: shared_preferences_windows
+      sha256: "94ef0f72b2d71bc3e700e025db3710911bd51a71cefb65cc609dd0d9a982e3c1"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
   shelf:
     dependency: transitive
     description: