*: default to `debug` log level when built in debug

!feat: downgrade `cairo`, `pango`, `pangocairo` to 0.21.5 for building on OpenBSD

feat: use raw ffi for authentication

Merge pull request #66 from OldUser101/OldUser101/push-nszxypkklqmy

build(flake): update input `nixpkgs`

feat(nix): pass revision to build for version string

refactor(args): use `clap-derive` for argument parsing

fix: handle multi-byte unicode characters in password string

refactor(event): use custom cross-platform event system

feat(image): use cairo conversion for png images, reduce pixbuf overhead

feat: add subcommand for shell completion generation

refactor(render): validate surface and output width and height when setting

refactor(render): add Cairo extension trait for Rgba struct

chore(buffer): resolve unused import build warnings

refactor(buffer): add buffer guards to prevent unbounded allocations

doc: add Linux only note on configuration value