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>

doc/research/reference-sources/wf_DeliveryHelper.swift

@@ -0,0 +1,46 @@
+import Foundation
+import AnyCodable
+import FloatplaneAPIClient
+
+let rgxTemplateItemPattern = try! NSRegularExpression(pattern: #"\{([0-9a-z._$]*)\}"#, options: .caseInsensitive)
+
+class DeliveryHelper {
+	class func getBestUrl(variant: CdnDeliveryV3Variant, group: CdnDeliveryV3Group?) -> URL? {
+		// If the variant itself has an absolute URL, use that.
+		if let absoluteUrl = URL(string: variant.url), absoluteUrl.host != nil {
+			return absoluteUrl
+		}
+		
+		// Otherwise, get the best URL, in order of:
+		// 1. First try the variant's origins, if any
+		// 2. Try the group's origins, if any
+		// 3. Lastly, default to floatplane.com
+		
+		if let variantOrigins = variant.origins {
+			for randomElement in variantOrigins.shuffled() {
+				if let url = joinUrl(base: randomElement.url, remainder: variant.url) {
+					return url
+				}
+			}
+		}
+		
+		if let groupOrigins = group?.origins {
+			for randomElement in groupOrigins.shuffled() {
+				if let url = joinUrl(base: randomElement.url, remainder: variant.url) {
+					return url
+				}
+			}
+		}
+		
+		return joinUrl(base: "https://www.floatplane.com", remainder: variant.url)
+	}
+	
+	private class func joinUrl(base: String, remainder: String) -> URL? {
+		let cleanBase = base.trimmingSuffix(while: { $0 == "/" })
+		if remainder.hasPrefix("/") {
+			return URL(string: String(cleanBase) + String(remainder))
+		} else {
+			return URL(string: String(cleanBase) + "/" + String(remainder))
+		}
+	}
+}