feat(std): overhaul core utilities and debugging

[LunaStev]

Summary

• expand std::time with normalized durations, UTC DateTime, ISO 8601 parsing/formatting, portable clocks, and reliable sleep providers
• overhaul std::bytes with unsigned endian operations, checked byte views, random access, and transactional reader/writer cursors
• extend std::math with checked arithmetic, bit operations, IEEE-754 helpers, roots, and trigonometry
• harden std::mem and std::buffer against overflow, invalid bounds, aliasing, dangling pointers, and allocator errors
• add lightweight std::debug logging, value tracing, assertions, and fatal diagnostics
• make page-size and time providers portable across Linux, macOS, Windows, and FreeBSD
• fix frontend and LLVM lowering for entry-point ABI, integer literal context, unsigned arithmetic/conversions/widening, and pointer offsets/indexes
• bump the standard-library compatibility revision to 3 and strengthen the std policy check

Compatibility

This intentionally replaces the unsafe caller-sized TypedBuffer<T> API. The language does not expose size_of<T> or align_of<T>, so the previous API could not enforce a valid typed storage contract.

Validation

• cargo fmt --all --check
• cargo test --locked --all-targets --jobs 2 — 56 tests passed
• cargo clippy --locked --all-targets --jobs 2 -- -D warnings
• RUSTDOCFLAGS='-D warnings' cargo doc --locked --no-deps --jobs 2
• tools/check_std_policy.sh
• git diff --check
• Wave corpus: 224/224 passed
• standard-library examples: 21/21 passed
• E2E: 118 normal passes, 2 expected non-zero passes, 8 host/environment skips, 0 failures
• cross-target object matrix: core modules 81/81 and std::debug 27/27 across Linux, macOS, Windows, and FreeBSD targets