fix(worker): escape newline/tab in CLI args

src/ClaudeDo.Worker/Runner/ClaudeArgsBuilder.cs

@@ -55,9 +55,15 @@ public sealed class ClaudeArgsBuilder
 
     private static string Escape(string value)
     {
-        if (value.Contains(' ') || value.Contains('"') || value.Contains('\''))
+        if (value.Contains(' ') || value.Contains('"') || value.Contains('\'')
+            || value.Contains('\t') || value.Contains('\n') || value.Contains('\r'))
         {
-            var escaped = value.Replace("\\", "\\\\").Replace("\"", "\\\"");
+            var escaped = value
+                .Replace("\\", "\\\\")
+                .Replace("\"", "\\\"")
+                .Replace("\n", "\\n")
+                .Replace("\r", "\\r")
+                .Replace("\t", "\\t");
             return $"\"{escaped}\"";
         }
         return value;

tests/ClaudeDo.Worker.Tests/Runner/ClaudeArgsBuilderTests.cs

@@ -68,4 +68,28 @@ public sealed class ClaudeArgsBuilderTests
         var args = _builder.Build(new ClaudeRunConfig(null, """Don't say "hello".""", null, null));
         Assert.Contains("--append-system-prompt", args);
     }
+
+    [Fact]
+    public void Build_quotes_system_prompt_with_newline()
+    {
+        var args = _builder.Build(new ClaudeRunConfig(
+            Model: null,
+            SystemPrompt: "line1\nline2",
+            AgentPath: null,
+            ResumeSessionId: null));
+
+        Assert.Contains("--append-system-prompt \"line1\\nline2\"", args);
+    }
+
+    [Fact]
+    public void Build_quotes_system_prompt_with_tab()
+    {
+        var args = _builder.Build(new ClaudeRunConfig(
+            Model: null,
+            SystemPrompt: "col1\tcol2",
+            AgentPath: null,
+            ResumeSessionId: null));
+
+        Assert.Contains("\"col1", args);
+    }
 }