Fix Crat pass edge cases

[Medowhill]

Summary

• Tightens IO transformations for scanf, fscanf, fgets, and fprintf so translated code preserves whitespace and scanset behavior, tracks EOF handling, parses unsigned negative inputs consistently, and formats struct-backed strings correctly.
• Fixes pointer and allocation rewrites around escaped malloc ownership, allocator wrapper initialization, raw returns from owned pointer replacements, calloc boxed slice lengths, array-field pointer arithmetic, and raw outparam receiver promotion.
• Improves static and interface transformations by constraining RefCell borrow scopes for call arguments and generating wrappers that preserve exported names.
• Fixes libc and dependency edge cases including ASCII ctype classification, consistent magic slice length handling, and preserving existing bytemuck dependency configuration.
• Adds regression coverage across the affected IO, libc, pointer, and static replacement paths.

Validation

Summary:

• Test Cases Discovered: 338
• Test Cases Skipped: 2
• Test Cases Tested: 336
• Test Cases Failed: 2
• Test Vectors Passed: 2603
• Test Vectors Skipped: 155
• Test Vectors Failed: 11