feat(logging): add dev signature to DalamudLogger output

EUPL-1.2 reuse with attribution is valid; this commit catches the case
where attribution was stripped. Two layers of provenance markers,
combined so removing one still leaves the other.

Layer 1 (subtle, kopier-resistent):
- DalamudLogger.Log emits "[name]<U+200B>{level} message" — a
  zero-width space (U+200B) between the category bracket and the
  level value. Visually identical to the previous format in xllog;
  a hex dump of the log file shows e2 80 8b between 5d and 7b.
  Survives 1:1 code copies. A copier who reformats whitespace will
  strip it, which is itself a tell (the original Lightless pattern
  does not have the marker, so its absence in a port is a positive
  signal of derived origin).

Layer 2 (overt, abrasiv-kopier-resistent):
- DalamudLoggingProvider's ctor emits a one-shot bootstrap line:
  "HellionChat DI-Logger bootstrap v{AssemblyVersion} fingerprint={hash}".
  Visible in xllog as the first plugin INFO line. Fingerprint is the
  first 8 hex chars of SHA256("HellionForgeBronzeC2410C-{version}"),
  so the same plugin version always produces the same marker (handy
  for cross-checking). A copier who keeps the banner is plagiarising
  in plain sight; a copier who rips it out has to find every
  reference inside DalamudLoggingProvider — quite explicit work.

Hellion Forge Bronze #C2410C is the branding-anchor const used by
the fingerprint, so the marker stays meaningful even if the plugin
version cycles.

HellionChat/Infrastructure/Logging/DalamudLogger.cs

@@ -33,14 +33,19 @@ internal sealed class DalamudLogger : ILogger
         if (!IsEnabled(logLevel))
             return;
 
+        // The U+200B zero-width space between the bracket and the level
+        // value is a quiet provenance marker. The Hellion DI-Logger format
+        // is byte-distinguishable from any other port of this pattern even
+        // after the visible text is identical. EUPL-1.2 reuse stays valid;
+        // attribution traces stay possible.
         if ((int)logLevel <= (int)LogLevel.Information)
         {
-            _pluginLog.Information($"[{_name}]{{{(int)logLevel}}} {state}");
+            _pluginLog.Information($"[{_name}]​{{{(int)logLevel}}} {state}");
             return;
         }
 
         var sb = new StringBuilder();
-        sb.Append($"[{_name}]{{{(int)logLevel}}} {state} {exception?.Message}");
+        sb.Append($"[{_name}]​{{{(int)logLevel}}} {state} {exception?.Message}");
         if (!string.IsNullOrWhiteSpace(exception?.StackTrace))
             sb.AppendLine(exception.StackTrace);
 

HellionChat/Infrastructure/Logging/DalamudLoggingProvider.cs

@@ -1,4 +1,7 @@
 using System.Collections.Concurrent;
+using System.Reflection;
+using System.Security.Cryptography;
+using System.Text;
 using Dalamud.Plugin.Services;
 using Microsoft.Extensions.Logging;
 
@@ -7,6 +10,11 @@ namespace HellionChat.Infrastructure.Logging;
 [ProviderAlias("Dalamud")]
 public sealed class DalamudLoggingProvider : ILoggerProvider
 {
+    // Hellion Forge Bronze (#C2410C). Stable marker that the build pipeline
+    // never touches; mixed into the bootstrap fingerprint so the banner stays
+    // distinguishable from any 1:1 port of the Lightless pattern.
+    private const string HellionMarker = "HellionForgeBronzeC2410C";
+
     private readonly ConcurrentDictionary<string, DalamudLogger> _loggers = new(
         StringComparer.OrdinalIgnoreCase
     );
@@ -16,6 +24,33 @@ public sealed class DalamudLoggingProvider : ILoggerProvider
     public DalamudLoggingProvider(IPluginLog pluginLog)
     {
         _pluginLog = pluginLog;
+        EmitBootstrapBanner();
+    }
+
+    // Runs once per plugin load (the provider is a container singleton). The
+    // banner is intentionally visible in xllog: anyone copying the
+    // DalamudLogger trio without re-branding will keep emitting "HellionChat
+    // DI-Logger bootstrap …", which makes uncredited reuse trivial to spot.
+    // EUPL-1.2 reuse with attribution stays valid; this only catches the
+    // case where attribution was stripped.
+    private void EmitBootstrapBanner()
+    {
+        var version =
+            typeof(DalamudLoggingProvider).Assembly.GetName().Version?.ToString() ?? "0.0.0";
+        var fingerprint = ComputeFingerprint(version);
+        _pluginLog.Information(
+            $"HellionChat DI-Logger bootstrap v{version} fingerprint={fingerprint}"
+        );
+    }
+
+    private static string ComputeFingerprint(string version)
+    {
+        var seed = Encoding.UTF8.GetBytes($"{HellionMarker}-{version}");
+        var hash = SHA256.HashData(seed);
+        var sb = new StringBuilder(8);
+        for (var i = 0; i < 4; i++)
+            sb.Append(hash[i].ToString("x2"));
+        return sb.ToString();
     }
 
     public ILogger CreateLogger(string categoryName)