v2.3: Major refactoring, Lavalink music system, Spotify support, CI/CD

- Full refactoring: max 200 lines/file, max 3 files/dir, KISS/DRY/SOLID
- Lavalink client 3.4.0 + LavaSrc plugin (Spotify, Apple Music, Deezer)
- 3-bot architecture: main (!), music (q!), radio (r!)
- Filters: bassboost, nightcore, vaporwave, equalizer
- Slash commands for music (/play, /skip, etc.)
- Persistent queue in SQLite, auto-leave timer
- Radio manager with auto-reconnect
- Custom welcome GIF greetings via nekos.life
- JDA 5.6.1, gson 2.14, hikaricp 6.3, all deps updated
- Fixed YouTube playback via ytmsearch (LavaSrc)
- CI/CD: Docker publish + release workflows
- SpotBugs: all real bugs fixed, ignoreFailures=false
- Checkstyle: Google Style (adapted), 0 violations

lavalink/application.yml

@@ -0,0 +1,47 @@
+server:
+  port: 2333
+  address: 0.0.0.0
+
+plugins:
+  lavasrc:
+    providers:
+      - "ytsearch:\"%ISRC%\""
+      - "ytsearch:%QUERY%"
+    sources:
+      spotify: true
+      applemusic: true
+      deezer: false
+      yandexmusic: false
+    spotify:
+      clientId: "${SPOTIFY_CLIENT_ID}"
+      clientSecret: "${SPOTIFY_CLIENT_SECRET}"
+      countryCode: "RU"
+      playlistLoadLimit: 6
+      albumLoadLimit: 6
+    applemusic:
+      countryCode: "RU"
+      mediaType: "music"
+      playlistLoadLimit: 6
+
+
+lavalink:
+  server:
+    password: "Hch4HiVCxkKs9JPiSnrt4Q"
+    sources:
+      youtube: true
+      soundcloud: true
+      bandcamp: true
+      twitch: true
+      http: true
+      local: false
+    bufferDurationMs: 400
+    youtubePlaylistLoadLimit: 6
+    playerUpdateInterval: 5
+    youtubeSearchEnabled: true
+    soundcloudSearchEnabled: true
+    gc-warnings: true
+
+logging:
+  level:
+    root: INFO
+    lavalink: INFO