Add /music/sources endpoint to list playable music sources

Introduced a new GET route `/music/sources` to retrieve supported music source types. Added `MusicSourceResponse` DTO for OpenAPI schema integration and implemented filtering logic to exclude unsupported types. Updated `MusicRoutes` to register the new endpoint.

src/main/java/me/bobert/netneutrality/http/server/MusicRoutes.java

@@ -19,18 +19,21 @@ import io.javalin.openapi.OpenApiResponse;
 import me.bobert.netneutrality.core.command.CommandExecutionResult;
 import me.bobert.netneutrality.http.server.dto.CommandResultResponse;
 import me.bobert.netneutrality.http.server.dto.ErrorResponse;
+import me.bobert.netneutrality.http.server.dto.MusicSourceResponse;
 import me.bobert.netneutrality.http.server.dto.MusicStatusResponse;
 import me.bobert.netneutrality.http.server.dto.QueuedTrackResponse;
 import me.bobert.netneutrality.http.server.dto.VolumeRequest;
 import me.bobert.netneutrality.http.server.dto.VolumeResponse;
 import me.bobert.netneutrality.music.MusicManager;
 import me.bobert.netneutrality.music.MusicService;
+import me.bobert.netneutrality.music.SourceFinder;
 import me.bobert.netneutrality.music.TrackInfo;
 import net.dv8tion.jda.api.JDA;
 import net.dv8tion.jda.api.entities.Guild;
 import net.dv8tion.jda.api.entities.Member;
 import net.dv8tion.jda.api.entities.channel.middleman.AudioChannel;
 
+import java.util.Arrays;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.function.Supplier;
@@ -48,6 +51,7 @@ public final class MusicRoutes {
     }
 
     public static void register(RoutesConfig routes, Supplier<JDA> jdaSupplier, MusicService musicService) {
+        routes.get("/music/sources", MusicRoutes::sources);
         routes.get("/music/{guildId}/status", ctx -> status(jdaSupplier, musicService, ctx));
         routes.get("/music/{guildId}/queue", ctx -> queue(jdaSupplier, musicService, ctx));
         routes.post("/music/{guildId}/skip", ctx -> skip(jdaSupplier, musicService, ctx));
@@ -56,6 +60,22 @@ public final class MusicRoutes {
         routes.post("/music/{guildId}/vote-skip/{userId}", ctx -> voteSkip(jdaSupplier, musicService, ctx));
     }
 
+    @OpenApi(
+        path = "/music/sources",
+        methods = HttpMethod.GET,
+        summary = "List the music sources the bot can play tracks from",
+        tags = {"Music"},
+        responses = @OpenApiResponse(status = "200", content = @OpenApiContent(from = MusicSourceResponse[].class))
+    )
+    private static void sources(Context ctx) {
+        ctx.json(
+            Arrays.stream(SourceFinder.AudioSourceType.values())
+                .filter(type -> type != SourceFinder.AudioSourceType.Nothing)
+                .map(type -> new MusicSourceResponse(type.name()))
+                .toList()
+        );
+    }
+
     @OpenApi(
         path = "/music/{guildId}/status",
         methods = HttpMethod.GET,

src/main/java/me/bobert/netneutrality/http/server/dto/MusicSourceResponse.java

@@ -0,0 +1,15 @@
+package me.bobert.netneutrality.http.server.dto;
+
+/*
+ * Copyright (c) anthorob
+ *
+ * https://discord.gg/qUa6zNFZsd
+ */
+
+/**
+ * OpenAPI schema for a {@code /music/sources} entry.
+ */
+public record MusicSourceResponse(
+    String name
+) {
+}