refactor: phase 5 transpiler docs, mod-compat helpers, and build quality gates

UXAssist/Common/Patching/TranspilerGuard.cs

@@ -0,0 +1,28 @@
+using System.Collections.Generic;
+using System.Reflection.Emit;
+using BepInEx.Logging;
+using HarmonyLib;
+
+namespace UXAssist.Common.Patching;
+
+/// <summary>
+/// Helper for Harmony transpilers. Provides a standardized way to bail out and return the original
+/// instructions when a <see cref="CodeMatcher"/> fails to match, which makes version-fragile patches
+/// easier to diagnose at runtime.
+/// </summary>
+public static class TranspilerGuard
+{
+    public static IEnumerable<CodeInstruction> Finish(
+        this CodeMatcher matcher,
+        IEnumerable<CodeInstruction> originalInstructions,
+        ManualLogSource logger,
+        string transpilerName)
+    {
+        if (matcher.IsInvalid)
+        {
+            logger?.LogWarning($"Transpiler '{transpilerName}' failed to match; returning original instructions.");
+            return originalInstructions;
+        }
+        return matcher.InstructionEnumeration();
+    }
+}