Bugfix/reading time format issue 451 (#456)

* Fix reading time display affected by 12/24-hour system setting (#451)

Reading time was incorrectly displayed as time-of-day (e.g., "12:45:00 AM" on 12-hour format devices) instead of as a duration. This occurred because DateFormatter was being used to format what should be a duration value, causing it to apply system time format preferences.

Replaced DateFormatter with simple duration calculation that formats as HH:MM:SS regardless of device settings. Added comprehensive unit tests covering basic durations, hour boundaries, fractional minutes, and edge cases.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

* Add GitHub Action to run SharedLib tests

---------

Co-authored-by: Claude <noreply@anthropic.com>

.github/workflows/sharedlib-tests.yml

@@ -0,0 +1,33 @@
+name: SharedLib Tests
+
+on:
+  push:
+    branches: [ main ]
+    paths:
+      - 'SharedLib/**'
+      - '.github/workflows/sharedlib-tests.yml'
+  pull_request:
+    branches: [ main ]
+    paths:
+      - 'SharedLib/**'
+      - '.github/workflows/sharedlib-tests.yml'
+
+jobs:
+  test:
+    name: Run SharedLib Tests
+    runs-on: macos-latest
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Select Xcode version
+      run: sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
+
+    - name: Show Swift version
+      run: swift --version
+
+    - name: Run SharedLib tests
+      run: |
+        cd SharedLib
+        swift test

SharedLib/Sources/SharedLib/Extension/Double.swift

@@ -2,11 +2,11 @@ import Foundation
 
 public extension Double {
     var readingTime: String {
-        let date = Date(timeIntervalSince1970: TimeInterval(self * 60))
-        let dayTimePeriodFormatter = DateFormatter()
-        dayTimePeriodFormatter.timeZone = TimeZone(secondsFromGMT: 0)
-        dayTimePeriodFormatter.dateFormat = "HH:mm:ss"
+        let totalSeconds = Int(self * 60)
+        let hours = totalSeconds / 3600
+        let minutes = (totalSeconds % 3600) / 60
+        let seconds = totalSeconds % 60
 
-        return dayTimePeriodFormatter.string(from: date as Date)
+        return String(format: "%02d:%02d:%02d", hours, minutes, seconds)
     }
 }

SharedLib/Sources/SharedLib/Extension/Int.swift

@@ -2,12 +2,12 @@ import Foundation
 
 public extension Int {
     var readingTime: String {
-        let date = Date(timeIntervalSince1970: TimeInterval(self * 60))
-        let dayTimePeriodFormatter = DateFormatter()
-        dayTimePeriodFormatter.timeZone = TimeZone(secondsFromGMT: 0)
-        dayTimePeriodFormatter.dateFormat = "HH:mm:ss"
+        let totalSeconds = self * 60
+        let hours = totalSeconds / 3600
+        let minutes = (totalSeconds % 3600) / 60
+        let seconds = totalSeconds % 60
 
-        return dayTimePeriodFormatter.string(from: date as Date)
+        return String(format: "%02d:%02d:%02d", hours, minutes, seconds)
     }
 
     var bool: Bool {

SharedLib/Tests/SharedLibTests/Extension/DoubleTests.swift

@@ -0,0 +1,35 @@
+import XCTest
+
+class DoubleTests: XCTestCase {
+    func testReadingTime() {
+        // Basic minute tests
+        XCTAssertEqual("00:01:00", 1.0.readingTime)
+        XCTAssertEqual("00:02:00", 2.0.readingTime)
+        XCTAssertEqual("00:05:00", 5.0.readingTime)
+        XCTAssertEqual("00:10:00", 10.0.readingTime)
+        XCTAssertEqual("00:30:00", 30.0.readingTime)
+        XCTAssertEqual("00:45:00", 45.0.readingTime)
+
+        // Hour boundary tests
+        XCTAssertEqual("01:00:00", 60.0.readingTime)
+        XCTAssertEqual("01:01:00", 61.0.readingTime)
+        XCTAssertEqual("01:30:00", 90.0.readingTime)
+
+        // Multiple hours
+        XCTAssertEqual("02:00:00", 120.0.readingTime)
+        XCTAssertEqual("02:15:00", 135.0.readingTime)
+        XCTAssertEqual("03:45:00", 225.0.readingTime)
+
+        // Fractional minutes (should truncate seconds properly)
+        XCTAssertEqual("00:01:30", 1.5.readingTime)
+        XCTAssertEqual("00:02:15", 2.25.readingTime)
+        XCTAssertEqual("00:05:45", 5.75.readingTime)
+
+        // Edge cases
+        XCTAssertEqual("00:00:00", 0.0.readingTime)
+
+        // Long reading times
+        XCTAssertEqual("10:00:00", 600.0.readingTime)
+        XCTAssertEqual("24:00:00", 1440.0.readingTime)
+    }
+}

SharedLib/Tests/SharedLibTests/Extension/IntTests.swift

@@ -2,9 +2,30 @@ import XCTest
 
 class IntTests: XCTestCase {
     func testReadingTime() {
+        // Basic minute tests
         XCTAssertEqual("00:01:00", 1.readingTime)
         XCTAssertEqual("00:02:00", 2.readingTime)
+        XCTAssertEqual("00:05:00", 5.readingTime)
+        XCTAssertEqual("00:10:00", 10.readingTime)
+        XCTAssertEqual("00:30:00", 30.readingTime)
+        XCTAssertEqual("00:45:00", 45.readingTime)
+
+        // Hour boundary tests
+        XCTAssertEqual("01:00:00", 60.readingTime)
         XCTAssertEqual("01:01:00", 61.readingTime)
+        XCTAssertEqual("01:30:00", 90.readingTime)
+
+        // Multiple hours
+        XCTAssertEqual("02:00:00", 120.readingTime)
+        XCTAssertEqual("02:15:00", 135.readingTime)
+        XCTAssertEqual("03:45:00", 225.readingTime)
+
+        // Edge cases
+        XCTAssertEqual("00:00:00", 0.readingTime)
+
+        // Long reading times
+        XCTAssertEqual("10:00:00", 600.readingTime)
+        XCTAssertEqual("24:00:00", 1440.readingTime)
     }
 
     func testBool() {