feat(network): support custom relay servers

Add strict custom Iroh relay profiles with safe restart and rollback across the Rust core, Compose apps, and Apple apps. Preserve multi-relay invitations and fail closed on configuration or recovery mismatches.

apple/Tests/RelayConfigurationTests.swift

@@ -0,0 +1,95 @@
+import XCTest
+@testable import VniDrop
+
+final class RelayConfigurationTests: XCTestCase {
+	func testAutomaticModeIgnoresRelayDrafts() throws {
+		let result = try RelayConfigurationValidator.validate(
+			mode: .automatic,
+			relayURLs: ["not a URL"]
+		)
+		XCTAssertEqual(result, .automatic)
+	}
+
+	func testAutomaticModeRetainsPreviouslySavedRelayURLs() throws {
+		let result = try RelayConfigurationValidator.validate(
+			mode: .automatic,
+			relayURLs: ["not a URL"],
+			retainedRelayURLs: ["https://relay.example"]
+		)
+		XCTAssertEqual(result, RelayConfiguration(
+			mode: .automatic,
+			relayURLs: ["https://relay.example"]
+		))
+	}
+
+	func testCustomModeTrimsValidHTTPSRelayURLs() throws {
+		let result = try RelayConfigurationValidator.validate(
+			mode: .custom,
+			relayURLs: ["  https://relay.example/  ", "https://backup.example:443"]
+		)
+		XCTAssertEqual(result, RelayConfiguration(
+			mode: .custom,
+			relayURLs: ["https://relay.example", "https://backup.example"]
+		))
+	}
+
+	func testCustomModeIgnoresEmptyURLRows() throws {
+		let result = try RelayConfigurationValidator.validate(
+			mode: .custom,
+			relayURLs: ["", "  ", "https://relay.example"]
+		)
+		XCTAssertEqual(result.relayURLs, ["https://relay.example"])
+	}
+
+	func testCustomModeRequiresAtLeastOneRelay() {
+		XCTAssertThrowsError(try RelayConfigurationValidator.validate(mode: .custom, relayURLs: [])) { error in
+			XCTAssertEqual(error as? RelayConfigurationValidationError, .missingURL)
+		}
+	}
+
+	func testCustomModeRequiresHTTPS() {
+		XCTAssertThrowsError(try RelayConfigurationValidator.validate(
+			mode: .custom,
+			relayURLs: ["http://relay.example"]
+		)) { error in
+			XCTAssertEqual(error as? RelayConfigurationValidationError, .httpsRequired(index: 0))
+		}
+	}
+
+	func testCustomModeRejectsCredentialsQueryFragmentAndPath() {
+		let invalidURLs = [
+			"https://user:password@relay.example",
+			"https://relay.example?token=secret",
+			"https://relay.example#fragment",
+			"https://relay.example/custom/path",
+			"https://relay.example:0",
+			"https://relay.example:99999",
+		]
+		for relayURL in invalidURLs {
+			XCTAssertThrowsError(
+				try RelayConfigurationValidator.validate(mode: .custom, relayURLs: [relayURL]),
+				"Expected \(relayURL) to be rejected"
+			) { error in
+				XCTAssertEqual(error as? RelayConfigurationValidationError, .invalidURL(index: 0))
+			}
+		}
+	}
+
+	func testCustomModeRejectsNormalizedDuplicate() {
+		XCTAssertThrowsError(try RelayConfigurationValidator.validate(
+			mode: .custom,
+			relayURLs: ["https://relay.example", "https://RELAY.example:443/"]
+		)) { error in
+			XCTAssertEqual(error as? RelayConfigurationValidationError, .duplicateURL(index: 1))
+		}
+	}
+
+	func testCustomModeRejectsMoreThanEightRelays() {
+		let relayURLs = (0...RelayConfigurationValidator.maximumRelayCount).map {
+			"https://relay-\($0).example"
+		}
+		XCTAssertThrowsError(try RelayConfigurationValidator.validate(mode: .custom, relayURLs: relayURLs)) { error in
+			XCTAssertEqual(error as? RelayConfigurationValidationError, .tooManyURLs)
+		}
+	}
+}