fix: harden and package Windows kernel tools

[FreddyJD]

Summary

• validate every fixed-size UTF-16 path and registry request in the driver
• reject empty required strings, embedded NULs, and oversized bridge inputs instead of truncating them
• zero directory query/output buffers and handle empty directories without parsing uninitialized data
• validate every returned directory record boundary, filename length, and next-record offset
• enumerate validated directory batches up to the protocol cap
• preserve the existing wire layout while avoiding misaligned typed output writes
• reject impossible file-list counts in the Rust bridge

Validation

• cargo fmt -- --check
• cargo test (7 passed)
• cargo clippy --bin roxy-kernel-bridge -- -D warnings
• cargo build --release
• git diff --check

Native driver compilation was attempted but remains blocked on this workstation because Visual Studio cannot find the WindowsKernelModeDriver10.0 platform toolset. The Windows SDK headers/tools are present, but WDK Visual Studio integration is not installed correctly.