feat: transformation en application Radyobòkaz Player (WIP sécurisé)

Fork de la librairie headless svelte-podcast transformé en lecteur :
radio Funkwhale mizik.o-k-i.net (~2000 titres), page démo RSS Syntax.fm,
file de lecture, préférences et progression persistées.

État avant refonte playbook OKI (bugs connus : volume inerte,
bouton démo RSS cassé en navigation client, cibles tactiles mobiles).

src/radio/library-store.ts

@@ -0,0 +1,93 @@
+import { get, writable } from 'svelte/store';
+import {
+	fetch_radio_page,
+	RADIO_PAGE_SIZE,
+	type RadioTrack,
+} from './funkwhale';
+import { radio_player } from './radio-store';
+
+/**
+ * State of the browsable library (all tracks of the radio).
+ */
+export interface LibraryState {
+	tracks: RadioTrack[];
+	/** Total number of tracks on the radio (known after the first page). */
+	total: number | null;
+	loaded_pages: number;
+	total_pages: number | null;
+	is_loading: boolean;
+	is_done: boolean;
+	error: string | null;
+}
+
+const initial_state: LibraryState = {
+	tracks: [],
+	total: null,
+	loaded_pages: 0,
+	total_pages: null,
+	is_loading: false,
+	is_done: false,
+	error: null,
+};
+
+export const library = writable<LibraryState>(initial_state);
+
+/**
+ * Loads every page of the radio's track list, one after another.
+ * Idempotent: does nothing if already loading or fully loaded.
+ */
+export async function load_library(): Promise<void> {
+	const state = get(library);
+	if (state.is_loading || state.is_done) return;
+
+	library.set({ ...state, is_loading: true, error: null });
+
+	try {
+		// First page: tells us how many tracks / pages exist.
+		const first = await fetch_radio_page(1);
+		const total_pages = Math.ceil(first.count / RADIO_PAGE_SIZE);
+		library.set({
+			tracks: first.tracks,
+			total: first.count,
+			loaded_pages: 1,
+			total_pages,
+			is_loading: true,
+			is_done: total_pages <= 1,
+			error: null,
+		});
+
+		// Load remaining pages in small parallel batches.
+		const CONCURRENCY = 4;
+		for (let start = 2; start <= total_pages; start += CONCURRENCY) {
+			// Pause while playback is loading a track: streaming and
+			// playback-related requests have priority over the library.
+			while (get(radio_player).is_loading) {
+				await new Promise((resolve) => setTimeout(resolve, 300));
+			}
+
+			const pages = await Promise.all(
+				Array.from(
+					{ length: Math.min(CONCURRENCY, total_pages - start + 1) },
+					(_, i) => fetch_radio_page(start + i),
+				),
+			);
+			library.update((prev) => ({
+				...prev,
+				tracks: [...prev.tracks, ...pages.flatMap((p) => p.tracks)],
+				loaded_pages: Math.min(start + CONCURRENCY - 1, total_pages),
+			}));
+		}
+
+		library.update((prev) => ({
+			...prev,
+			is_loading: false,
+			is_done: true,
+		}));
+	} catch (error) {
+		library.update((prev) => ({
+			...prev,
+			is_loading: false,
+			error: error instanceof Error ? error.message : String(error),
+		}));
+	}
+}