Add unit tests for various services and functionalities

- Implement tests for ChatLine utility methods including color tag detection and stripping.
- Create comprehensive tests for CommandHandler to validate command handling and status updates.
- Add tests for DataMigrationService to ensure correct ANSI to color tag conversion.
- Enhance FileValidationHelperTests with audio file validation tests.
- Introduce ImageToAsciiServiceTests to verify image dimension retrieval.
- Develop IrcMessageFormatterTests for message formatting and color tag conversion.
- Add JwtTokenServiceTests to validate JWT token generation and hashing.
- Implement LinkEmbedServiceTests for URL extraction and Open Graph tag parsing.
- Update EchoHub.Tests.csproj to include necessary project references.

src/EchoHub.Tests/ChatLineTests.cs

@@ -0,0 +1,107 @@
+using EchoHub.Client.UI;
+using Xunit;
+
+namespace EchoHub.Tests;
+
+/// <summary>
+/// Tests for static string-utility methods on ChatLine.
+/// Note: Tests that construct ChatLine/ChatListSource or use Terminal.Gui types
+/// (Attribute, Color) are excluded because Terminal.Gui's module initializer
+/// requires a display driver which is unavailable in CI/test environments.
+/// </summary>
+public class ChatLineTests
+{
+    // ── HasColorTags ──────────────────────────────────────────────────
+
+    [Fact]
+    public void HasColorTags_ForegroundTag_ReturnsTrue()
+    {
+        Assert.True(ChatLine.HasColorTags("Hello {F:FF0000}world"));
+    }
+
+    [Fact]
+    public void HasColorTags_BackgroundTag_ReturnsTrue()
+    {
+        Assert.True(ChatLine.HasColorTags("Hello {B:00FF00}world"));
+    }
+
+    [Fact]
+    public void HasColorTags_ResetTag_ReturnsTrue()
+    {
+        Assert.True(ChatLine.HasColorTags("Hello{X}"));
+    }
+
+    [Fact]
+    public void HasColorTags_NoTags_ReturnsFalse()
+    {
+        Assert.False(ChatLine.HasColorTags("Hello world"));
+    }
+
+    [Fact]
+    public void HasColorTags_PartialTag_ReturnsFalse()
+    {
+        // {Z:...} is not a valid tag (only F or B)
+        Assert.False(ChatLine.HasColorTags("Hello {Z:000000}"));
+    }
+
+    [Fact]
+    public void HasColorTags_EmptyString_ReturnsFalse()
+    {
+        Assert.False(ChatLine.HasColorTags(""));
+    }
+
+    [Theory]
+    [InlineData("{F:AABBCC}text")]
+    [InlineData("prefix{B:112233}suffix")]
+    [InlineData("a{X}b")]
+    [InlineData("{F:000000}{B:FFFFFF}{X}")]
+    public void HasColorTags_VariousValidTags_ReturnsTrue(string input)
+    {
+        Assert.True(ChatLine.HasColorTags(input));
+    }
+
+    // ── StripColorTags ────────────────────────────────────────────────
+
+    [Fact]
+    public void StripColorTags_RemovesAllTags()
+    {
+        var result = ChatLine.StripColorTags("{F:FF0000}red{B:00FF00}green{X}");
+        Assert.Equal("redgreen", result);
+    }
+
+    [Fact]
+    public void StripColorTags_NoTags_ReturnsOriginal()
+    {
+        var result = ChatLine.StripColorTags("plain text");
+        Assert.Equal("plain text", result);
+    }
+
+    [Fact]
+    public void StripColorTags_OnlyTags_ReturnsEmpty()
+    {
+        var result = ChatLine.StripColorTags("{F:AABBCC}{B:112233}{X}");
+        Assert.Equal("", result);
+    }
+
+    [Fact]
+    public void StripColorTags_MixedContent_KeepsText()
+    {
+        var result = ChatLine.StripColorTags("before{F:FF0000}middle{X}after");
+        Assert.Equal("beforemiddleafter", result);
+    }
+
+    [Fact]
+    public void StripColorTags_MultipleConsecutiveTags_AllStripped()
+    {
+        var result = ChatLine.StripColorTags("{F:FF0000}{B:00FF00}{X}{F:0000FF}text{X}");
+        Assert.Equal("text", result);
+    }
+
+    [Fact]
+    public void StripColorTags_PreservesNonTagBraces()
+    {
+        // {Hello} is not a valid tag and should be preserved
+        var result = ChatLine.StripColorTags("{Hello} world");
+        Assert.Equal("{Hello} world", result);
+    }
+}