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/DataMigrationServiceTests.cs

@@ -0,0 +1,74 @@
+using EchoHub.Server.Setup;
+using Xunit;
+
+namespace EchoHub.Tests;
+
+public class DataMigrationServiceTests
+{
+    // ── AnsiToColorTags ───────────────────────────────────────────────
+
+    [Fact]
+    public void AnsiToColorTags_ForegroundEscape_ConvertedToColorTag()
+    {
+        var ansi = "\x1b[38;2;255;0;0mred text";
+        var result = DataMigrationService.AnsiToColorTags(ansi);
+
+        Assert.Equal("{F:FF0000}red text", result);
+    }
+
+    [Fact]
+    public void AnsiToColorTags_BackgroundEscape_ConvertedToColorTag()
+    {
+        var ansi = "\x1b[48;2;0;255;0mgreen bg";
+        var result = DataMigrationService.AnsiToColorTags(ansi);
+
+        Assert.Equal("{B:00FF00}green bg", result);
+    }
+
+    [Fact]
+    public void AnsiToColorTags_ResetEscape_ConvertedToResetTag()
+    {
+        var ansi = "\x1b[0m";
+        var result = DataMigrationService.AnsiToColorTags(ansi);
+
+        Assert.Equal("{X}", result);
+    }
+
+    [Fact]
+    public void AnsiToColorTags_NoEscapes_ReturnsUnchanged()
+    {
+        var text = "Hello, world!";
+        var result = DataMigrationService.AnsiToColorTags(text);
+
+        Assert.Equal("Hello, world!", result);
+    }
+
+    [Fact]
+    public void AnsiToColorTags_MixedContent_ConvertsEscapesOnly()
+    {
+        var ansi = "before\x1b[38;2;100;200;50mtextafter";
+        var result = DataMigrationService.AnsiToColorTags(ansi);
+
+        Assert.Equal("before{F:64C832}textafter", result);
+    }
+
+    [Fact]
+    public void AnsiToColorTags_MultipleTags_AllConverted()
+    {
+        var ansi = "\x1b[38;2;255;0;0mred\x1b[48;2;0;0;255mblue bg\x1b[0mreset";
+        var result = DataMigrationService.AnsiToColorTags(ansi);
+
+        Assert.Equal("{F:FF0000}red{B:0000FF}blue bg{X}reset", result);
+    }
+
+    [Fact]
+    public void AnsiToColorTags_RoundTrip_WithColorTagsToAnsi()
+    {
+        // AnsiToColorTags and IrcMessageFormatter.ColorTagsToAnsi should be inverses
+        var original = "{F:FF0000}red{B:00FF00}green{X}";
+        var ansi = EchoHub.Server.Irc.IrcMessageFormatter.ColorTagsToAnsi(original);
+        var backToTags = DataMigrationService.AnsiToColorTags(ansi);
+
+        Assert.Equal(original, backToTags);
+    }
+}