Adds automatic elevation, a smaller-corners option, and a modernized codebase. New

• The tool now requests administrator rights on launch, so starting it from Explorer, a shortcut or the installer brings up the standard UAC prompt instead of failing with "make sure you are running as admin". Note that every invocation now needs elevation, including --help.
• --small option for a subtler alternative to fully square corners (thanks @amnweb!) Changed
• Failures now say what actually went wrong. Where v1.2 printed status: 0x5, you now get Access is denied. (0x5), with the Windows error text alongside the code.
• The installer now tells you when the "run automatically on logon" scheduled task could not be created, instead of leaving it silently missing. Removed
• The --no-patching fallback. It pulled in Zydis (a full x86 disassembler) just for this one option, inflating the binary for a niche feature with worse visual results than the primary .rdata patching method, which has been the default all along and is now the only option. If you'd rather keep using it, v1.2 still has it. Normal usage (--disable/--enable/--small) is unaffected. Under the hood
• Modernized the codebase to C++23/26.
• Opens dwm.exe with just the memory read/write access the patch needs, rather than requesting full access to the process.
• Every Win32 handle is now owned by an RAII guard instead of being closed by hand on each exit path, so the process handle, snapshot, token and loaded module are all released even when an error cuts the patch short.
• Builds are now reproducible and carry a signed build-provenance attestation via GitHub Actions. Verify a download with: gh attestation verify -R rich-ayr/win11-toggle-rounded-corners
• Formatting is enforced in CI with clang-format.