v0.5.0 — Phase β-4 Media + Advanced Card-Types

Alle 7 Card-Types werden gerendert und können erstellt werden.
image-occlusion mit Touch-Drag-Mask-Editor (kein PencilKit — Server-
Schema erlaubt nur Rechtecke), audio-front mit AVAudioPlayer und
File-Picker.

- MediaUploadResponse-DTO, MaskRegion-Codable mit 0..1-Coordinates
- MaskRegions.parse/encode (1:1-Port aus cards-domain, Sortierung
  nach ID lexikographisch)
- CardFieldsBuilder.imageOcclusion mit stringified-JSON-mask_regions
  + audioFront
- CardsAPI.uploadMedia (Multipart, 25 MiB) + fetchMedia (streamed)
- MediaCache actor mit LRU 200 MB (contentModificationDate-Eviction)
- mediaCache Environment-Key
- RemoteImage + AudioPlayerButton SwiftUI-Views
- CardRenderer: imageOcclusion (Mask-Overlay über RemoteImage) +
  audioFront (AudioPlayerButton + back-Text auf Flip)
- MaskEditorView: Touch-Drag-Rechteck, Label-Edit, Delete
- CardEditorView erweitert: PhotosPicker für Image, fileImporter
  für Audio, Magic-Byte-MIME-Detection
- 6 neue Tests für MaskRegions (30 Total grün)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Sources/Core/Domain/Media.swift

@@ -0,0 +1,103 @@
+import Foundation
+
+/// Response von `POST /api/v1/media/upload`.
+struct MediaUploadResponse: Decodable, Sendable {
+    let id: String
+    let url: String
+    let mimeType: String
+    let kind: MediaKind
+    let sizeBytes: Int
+    let originalFilename: String?
+
+    enum CodingKeys: String, CodingKey {
+        case id
+        case url
+        case mimeType = "mime_type"
+        case kind
+        case sizeBytes = "size_bytes"
+        case originalFilename = "original_filename"
+    }
+}
+
+enum MediaKind: String, Codable, Sendable {
+    case image
+    case audio
+    case video
+    case other
+}
+
+/// Image-Occlusion-Mask-Region.
+/// `mask_regions`-Feld ist ein JSON-Array-**String** in `fields`,
+/// nicht ein Object — Server-Schema-Constraint (`fields: Record<string,string>`).
+struct MaskRegion: Codable, Hashable, Sendable, Identifiable {
+    let id: String
+    let x: Double // 0..1 relativ
+    let y: Double
+    let w: Double
+    let h: Double
+    let label: String?
+
+    init(id: String, x: Double, y: Double, w: Double, h: Double, label: String? = nil) {
+        self.id = id
+        self.x = x
+        self.y = y
+        self.w = w
+        self.h = h
+        self.label = label
+    }
+}
+
+/// Helpers zum Parsen/Serialisieren von `mask_regions` als JSON-String.
+enum MaskRegions {
+    /// 1:1-Port aus `cards-domain/image-occlusion.ts:parseMaskRegions`.
+    /// Bei Parse- oder Schema-Fehler: leere Liste. Sortiert nach ID
+    /// (lexikographisch, gleich wie Server-Sortierung).
+    static func parse(_ json: String) -> [MaskRegion] {
+        guard let data = json.data(using: .utf8) else { return [] }
+        guard let regions = try? JSONDecoder().decode([MaskRegion].self, from: data) else { return [] }
+        return regions.sorted { $0.id < $1.id }
+    }
+
+    /// Sub-Index → Region (Sortier-Reihenfolge).
+    static func region(for json: String, subIndex: Int) -> MaskRegion? {
+        let all = parse(json)
+        return all.indices.contains(subIndex) ? all[subIndex] : nil
+    }
+
+    /// Anzahl Regionen → Anzahl Sub-Index-Reviews.
+    static func count(_ json: String) -> Int {
+        parse(json).count
+    }
+
+    /// Serialisiert eine Liste zu einem JSON-Array-String fürs `fields`-Feld.
+    static func encode(_ regions: [MaskRegion]) -> String {
+        let encoder = JSONEncoder()
+        encoder.outputFormatting = [.sortedKeys]
+        guard let data = try? encoder.encode(regions) else { return "[]" }
+        return String(decoding: data, as: UTF8.self)
+    }
+}
+
+extension CardFieldsBuilder {
+    /// `image-occlusion`-Fields: `image_ref` (media_id) +
+    /// `mask_regions` (stringified JSON-Array) + optional `note`.
+    static func imageOcclusion(
+        imageRef: String,
+        regions: [MaskRegion],
+        note: String? = nil
+    ) -> [String: String] {
+        var fields: [String: String] = [
+            "image_ref": imageRef,
+            "mask_regions": MaskRegions.encode(regions),
+        ]
+        if let note, !note.isEmpty {
+            fields["note"] = note
+        }
+        return fields
+    }
+
+    /// `audio-front`-Fields: `audio_ref` (media_id) + `back` (Antwort-Text).
+    static func audioFront(audioRef: String, back: String) -> [String: String] {
+        ["audio_ref": audioRef, "back": back]
+    }
+}