Floatplane channel plugin for Jellyfin 10.10.x: browse, HLS proxy, cookie session, CI release

- IChannel: creators -> sub-channels -> video posts (public listing API, search mapped)
- IRequiresMediaInfoCallback -> signed proxy URLs; stream controller rewrites HLS so the
  AES-128 key is fetched server-side with the session cookie, segments stay on the CDN
- delivery/info cached per token lifetime and throttled (~2/min)
- config page: paste sails.sid + validate, extra creators, quality, search test
- scripts/package.sh -> plugin folder + zip + md5 + manifest.json; Gitea release workflow
- research docs, HAR analysis (HAR itself gitignored), install-pi5.sh

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Jellyfin.Plugin.Floatplane/Playback/HlsRewriter.cs

@@ -0,0 +1,94 @@
+using System;
+using System.Text;
+using System.Text.RegularExpressions;
+
+namespace Jellyfin.Plugin.Floatplane.Playback;
+
+/// <summary>
+/// Rewrites an HLS playlist so that (a) every media/segment URI is absolute and
+/// (b) the AES-128 key URI (which needs the Floatplane session cookie) and any nested
+/// playlist URIs point back at the plugin's proxy.
+/// </summary>
+public static partial class HlsRewriter
+{
+    [GeneratedRegex("URI=\"([^\"]*)\"", RegexOptions.CultureInvariant)]
+    private static partial Regex UriAttribute();
+
+    /// <param name="playlist">Playlist text as served by the CDN.</param>
+    /// <param name="playlistUrl">Absolute URL the playlist was fetched from (base for relative URIs).</param>
+    /// <param name="mapKeyUri">Maps the absolute key URI to the proxy key URL.</param>
+    /// <param name="mapPlaylistUri">Maps a nested playlist URI (master playlists) to a proxy URL; null = leave absolute.</param>
+    /// <param name="mapSegmentUri">Maps a segment URI; null = leave absolute (segments need no cookie).</param>
+    public static string Rewrite(
+        string playlist,
+        Uri playlistUrl,
+        Func<string, string> mapKeyUri,
+        Func<string, string>? mapPlaylistUri = null,
+        Func<string, string>? mapSegmentUri = null)
+    {
+        var sb = new StringBuilder(playlist.Length + 512);
+        var isMaster = playlist.Contains("#EXT-X-STREAM-INF", StringComparison.Ordinal);
+        var nextIsVariantPlaylist = false;
+
+        foreach (var rawLine in playlist.Split('\n'))
+        {
+            var line = rawLine.TrimEnd('\r');
+            if (line.Length == 0)
+            {
+                sb.Append('\n');
+                continue;
+            }
+
+            if (line.StartsWith('#'))
+            {
+                if (line.StartsWith("#EXT-X-KEY", StringComparison.Ordinal) || line.StartsWith("#EXT-X-SESSION-KEY", StringComparison.Ordinal))
+                {
+                    line = UriAttribute().Replace(line, m => "URI=\"" + mapKeyUri(Absolute(playlistUrl, m.Groups[1].Value)) + "\"", 1);
+                }
+                else if (line.StartsWith("#EXT-X-MAP", StringComparison.Ordinal))
+                {
+                    line = UriAttribute().Replace(line, m => "URI=\"" + MapSegment(Absolute(playlistUrl, m.Groups[1].Value), mapSegmentUri) + "\"", 1);
+                }
+                else if (line.StartsWith("#EXT-X-MEDIA", StringComparison.Ordinal) && mapPlaylistUri != null)
+                {
+                    line = UriAttribute().Replace(line, m => "URI=\"" + mapPlaylistUri(Absolute(playlistUrl, m.Groups[1].Value)) + "\"", 1);
+                }
+                else if (line.StartsWith("#EXT-X-STREAM-INF", StringComparison.Ordinal))
+                {
+                    nextIsVariantPlaylist = true;
+                }
+
+                sb.Append(line).Append('\n');
+                continue;
+            }
+
+            var absolute = Absolute(playlistUrl, line);
+            if (isMaster && nextIsVariantPlaylist)
+            {
+                nextIsVariantPlaylist = false;
+                sb.Append(mapPlaylistUri != null ? mapPlaylistUri(absolute) : absolute).Append('\n');
+            }
+            else
+            {
+                sb.Append(MapSegment(absolute, mapSegmentUri)).Append('\n');
+            }
+        }
+
+        return sb.ToString().TrimEnd('\n') + "\n";
+    }
+
+    private static string MapSegment(string absolute, Func<string, string>? mapSegmentUri)
+        => mapSegmentUri != null ? mapSegmentUri(absolute) : absolute;
+
+    /// <summary>Resolves <paramref name="reference"/> against <paramref name="baseUrl"/> (RFC 3986).</summary>
+    public static string Absolute(Uri baseUrl, string reference)
+    {
+        // Only http(s) is "absolute" here: on Linux Uri.TryCreate("/x.ts", Absolute) yields file:///x.ts.
+        if (Api.Models.DeliveryInfoModel.IsHttpUrl(reference))
+        {
+            return reference;
+        }
+
+        return new Uri(baseUrl, reference).ToString();
+    }
+}