Optimize timer frequency and eliminate redundant property wrappers

[Copilot]

Identified and fixed performance bottlenecks across models and views affecting battery life and rendering efficiency.

Changes

• TeaTimer: Reduced update frequency from 60Hz → 10Hz (6x fewer updates, sufficient for seconds-based display)
• ProgressBar: Moved computed variable out of body{} to struct level—was being recreated on every render
• Model properties: Removed trivial computed property wrappers from Tea, Cup, TeaSpoon, Temperature, Settings (160 lines eliminated)
• Minor cleanups: Simplified TimePeriod.isPositive() logic, removed unused @Published var aaa, removed no-op withAnimation wrapper

Before

struct Tea: Codable {
    private var _teaName: String
    var teaName: String {
        get { return _teaName }
        set { _teaName = newValue }
    }
}

// ProgressBar.swift
var body: some View {
    var progress: Double {  // ❌ Recreated every render
        get { ... }
        set { ... }
    }
    GeometryReader { ... }
}

After

struct Tea: Codable {
    var teaName: String
}

// ProgressBar.swift
private var progress: Double { ... }
private func updateProgress(_ newProgress: Double) { ... }
var body: some View {
    GeometryReader { ... }
}

Net -160 lines, maintains existing functionality.

Original prompt

Identify and suggest improvements to slow or inefficient code

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