feat: implement CIE 9.1 text file handling (OPENFILE/READFILE/WRITEFILE/CLOSEFILE/EOF)

Front end: OPENFILE/READFILE/WRITEFILE/CLOSEFILE plus reserved mode
keywords READ/WRITE/APPEND (RANDOM reserved with a dedicated
not-implemented error); statement nodes in new FileAST.h, parsing in new
ParserFile.cc; EOF joins the Builtins table as the 12th builtin and
CallExprAST now carries a line number for its runtime diagnostics.

Runtime: new FileHandler (StringHandler-shaped leaf) lazily synthesizes
internal __cps_file_* helper functions and a 16-slot open-file table
keyed by filename content (strcmp — STRING '=' is pointer identity).
EOF is an fgetc/ungetc peek; READFILE grows a malloc/realloc line buffer
and strips a trailing CR; fopen uses text modes so mingw-w64 line
translation works. File-free programs get byte-identical IR. All misuse
(not open, wrong mode, reopen, fopen failure, read past EOF, table full)
dies with the existing "[Fatal] line N:" pattern via a new
RuntimeCheck::emitErrorAndExit overload taking runtime printf args.

Also fixes a pre-existing ArithmeticHandler hole surfaced by adversarial
review: mixed-width integer operands (i1 BOOLEAN / i8 CHAR vs i64) now
widen via ZExt instead of emitting invalid IR, and remaining type
mismatches get a clean diagnostic; -EOF(f) and -IS_NUM(x) compile.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/cps/FileMode.h b/include/cps/FileMode.h
new file mode 100644
index 0000000..b95e615
--- /dev/null
+++ b/include/cps/FileMode.h
@@ -0,0 +1,11 @@
+#pragma once
+#include <cstdint>
+
+namespace cps {
+
+// Shared between FileAST (parser side) and FileHandler (codegen side).
+// The numeric values are the mode byte stored in the runtime file table;
+// 0 is reserved to mean "free slot".
+enum class FileMode : uint8_t { Read = 1, Write = 2, Append = 3 };
+
+} // namespace cps