add models module: shared types for accounts, messages, threads, sync

fix Package.swift: remove NIOIMAPCore product reference (only NIOIMAP is exported by swift-nio-imap)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Packages/MagnumOpusCore/Sources/Models/EmailAddress.swift

@@ -0,0 +1,32 @@
+import Foundation
+
+public struct EmailAddress: Sendable, Codable, Equatable, Hashable {
+	public var name: String?
+	public var address: String
+
+	public init(name: String? = nil, address: String) {
+		self.name = name
+		self.address = address
+	}
+
+	public var displayName: String {
+		name ?? address
+	}
+
+	/// Parses "Alice <alice@example.com>" or bare "alice@example.com"
+	public static func parse(_ raw: String) -> EmailAddress {
+		let trimmed = raw.trimmingCharacters(in: .whitespaces)
+		guard let openAngle = trimmed.lastIndex(of: "<"),
+			  let closeAngle = trimmed.lastIndex(of: ">"),
+			  openAngle < closeAngle
+		else {
+			return EmailAddress(address: trimmed)
+		}
+		let addr = String(trimmed[trimmed.index(after: openAngle)..<closeAngle])
+		let namepart = String(trimmed[..<openAngle]).trimmingCharacters(in: .whitespaces)
+		return EmailAddress(
+			name: namepart.isEmpty ? nil : namepart.trimmingCharacters(in: CharacterSet(charactersIn: "\"")),
+			address: addr
+		)
+	}
+}