iOS: fix audio generation to handle async 202 job flow + increase chapter list font size

- Replace AudioGenerateResponse with AudioTriggerResponse to handle both 200 (cached) and 202 (async job) responses
- Add pollAudioStatus() in APIClient that polls /api/audio/status every 2s until done or failed
- Update generateAudio() and prefetchNext() in AudioPlayerService to poll instead of expecting a synchronous URL response
- Bump chapter list font sizes: number xs→sm, title sm→base, date/badge xs→sm, row padding py-2→py-2.5

ios/LibNovel/LibNovel/Networking/APIClient.swift

@@ -241,11 +241,42 @@ actor APIClient {
 
     // MARK: - Audio
 
-    func triggerAudio(slug: String, chapter: Int, voice: String, speed: Double) async throws -> AudioGenerateResponse {
+    func triggerAudio(slug: String, chapter: Int, voice: String, speed: Double) async throws -> AudioTriggerResponse {
         struct Body: Encodable { let voice: String; let speed: Double }
         return try await fetch("/api/audio/\(slug)/\(chapter)", method: "POST", body: Body(voice: voice, speed: speed))
     }
 
+    /// Poll GET /api/audio/status/{slug}/{n}?voice=... until the job is done or failed.
+    /// Returns the presigned/proxy URL on success, throws on failure or cancellation.
+    func pollAudioStatus(slug: String, chapter: Int, voice: String) async throws -> String {
+        let path = "/api/audio/status/\(slug)/\(chapter)?voice=\(voice)"
+        struct StatusResponse: Decodable {
+            let status: String
+            let url: String?
+            let error: String?
+        }
+        while true {
+            try Task.checkCancellation()
+            let r: StatusResponse = try await fetch(path)
+            switch r.status {
+            case "done":
+                guard let url = r.url, !url.isEmpty else {
+                    throw URLError(.badServerResponse)
+                }
+                return url
+            case "failed":
+                throw NSError(
+                    domain: "AudioGeneration",
+                    code: 0,
+                    userInfo: [NSLocalizedDescriptionKey: r.error ?? "Audio generation failed"]
+                )
+            default:
+                // pending / generating / idle — keep polling
+                try await Task.sleep(nanoseconds: 2_000_000_000) // 2 s
+            }
+        }
+    }
+
     func presignAudio(slug: String, chapter: Int, voice: String) async throws -> String {
         struct Response: Decodable { let url: String }
         let r: Response = try await fetch("/api/presign/audio?slug=\(slug)&chapter=\(chapter)&voice=\(voice)")
@@ -406,11 +437,22 @@ struct SearchResponse: Decodable {
     }
 }
 
-struct AudioGenerateResponse: Decodable {
-    // The Go API is synchronous: it blocks until generation completes and
-    // returns {"url": "...", "filename": "..."} on success.
-    let url: String
-    let filename: String
+/// Returned by POST /api/audio/{slug}/{n}.
+/// - 202 Accepted: job enqueued → poll via pollAudioStatus()
+/// - 200 OK: audio already cached → url is ready to play
+struct AudioTriggerResponse: Decodable {
+    let jobId: String?   // present on 202
+    let status: String?  // present on 202: "pending" | "generating"
+    let url: String?     // present on 200: proxy URL ready to play
+    let filename: String? // present on 200
+
+    enum CodingKeys: String, CodingKey {
+        case jobId = "job_id"
+        case status, url, filename
+    }
+
+    /// True when the server accepted the request and created an async job.
+    var isAsync: Bool { jobId != nil }
 }
 
 struct ProgressEntry: Decodable, Identifiable {

ios/LibNovel/LibNovel/Services/AudioPlayerService.swift

@@ -165,14 +165,28 @@ final class AudioPlayerService: ObservableObject {
                 return
             }
 
-            // Slow path: trigger TTS generation. Go API blocks until done.
+            // Slow path: trigger TTS generation (async — returns 202 immediately).
             status = .generating
-            generationProgress = 50
-            let response = try await APIClient.shared.triggerAudio(slug: slug, chapter: chapter, voice: voice, speed: speed)
-            audioURL = response.url
+            generationProgress = 10
+            let trigger = try await APIClient.shared.triggerAudio(slug: slug, chapter: chapter, voice: voice, speed: speed)
+
+            let playableURL: String
+            if trigger.isAsync {
+                // 202 Accepted: poll until done.
+                generationProgress = 30
+                playableURL = try await APIClient.shared.pollAudioStatus(slug: slug, chapter: chapter, voice: voice)
+            } else {
+                // 200: already cached URL returned inline.
+                guard let url = trigger.url, !url.isEmpty else {
+                    throw URLError(.badServerResponse)
+                }
+                playableURL = url
+            }
+
+            audioURL = playableURL
             status = .ready
             generationProgress = 100
-            await playURL(response.url)
+            await playURL(playableURL)
             await prefetchNext()
         } catch is CancellationError {
             // Cancelled — no-op
@@ -197,9 +211,16 @@ final class AudioPlayerService: ObservableObject {
                 nextPrefetchStatus = .prefetched
                 return
             }
-            // Slow path: trigger generation so it's ready for next time.
-            let response = try await APIClient.shared.triggerAudio(slug: slug, chapter: next, voice: voice, speed: speed)
-            nextAudioURL = response.url
+            // Slow path: trigger generation; poll until done (background — won't block playback).
+            let trigger = try await APIClient.shared.triggerAudio(slug: slug, chapter: next, voice: voice, speed: speed)
+            let url: String
+            if trigger.isAsync {
+                url = try await APIClient.shared.pollAudioStatus(slug: slug, chapter: next, voice: voice)
+            } else {
+                guard let u = trigger.url, !u.isEmpty else { throw URLError(.badServerResponse) }
+                url = u
+            }
+            nextAudioURL = url
             nextPrefetchStatus = .prefetched
         } catch {
             nextPrefetchStatus = .failed