test(compiler): add repr control character escaping integration tests (#564)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: antonsynd

src/Sharpy.Compiler.Tests/Integration/TestFixtures/builtins/repr_escaping.expected

@@ -0,0 +1,14 @@
+'\x00'
+'\x07'
+'\x08'
+'\x0b'
+'\x0c'
+'\x1b'
+'\x1f'
+'\x7f'
+'\t'
+'\n'
+'\r'
+"it's \x07"
+'hello\x00world'
+'\\\x07'

src/Sharpy.Compiler.Tests/Integration/TestFixtures/builtins/repr_escaping.spy

@@ -0,0 +1,16 @@
+# Test repr() control character escaping
+def main():
+    print(repr("\x00"))
+    print(repr("\x07"))
+    print(repr("\x08"))
+    print(repr("\x0b"))
+    print(repr("\x0c"))
+    print(repr("\x1b"))
+    print(repr("\x1f"))
+    print(repr("\x7f"))
+    print(repr("\t"))
+    print(repr("\n"))
+    print(repr("\r"))
+    print(repr("it's \x07"))
+    print(repr("hello\x00world"))
+    print(repr("\\\x07"))