Fix factorial work distribution and update for Zig 0.16

[mjackson]

• Fix the factorial work distribution bug that returned a slice backed by stack memory and assumed a fixed 8-thread limit.
• Update the build script and command implementations for Zig 0.16's current build and stdlib APIs.
• Replace the temporary compatibility shim with direct Zig 0.16 I/O calls in the command modules.

[Copilot]

Pull request overview

Updates the ziglets CLI suite for Zig 0.16 APIs (notably the new std.Io I/O model and std.Build module setup) and addresses the factorial command’s work distribution implementation to avoid returning stack-backed slices / fixed thread limits.

Changes:

• Migrate command modules from std.io.getStd* to Zig 0.16 std.Io readers/writers.
• Rework factorial work distribution to allocate thread ranges dynamically.
• Update build.zig and main entrypoint/arg handling to Zig 0.16 build + process init APIs.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/ziglets/writer.zig	Updates file I/O and stdout printing to Zig 0.16 std.Io APIs.
src/ziglets/touch.zig	Ports stdout + filesystem calls to std.Io APIs.
src/ziglets/pgen.zig	Ports stdout writer typing and updates RNG usage.
src/ziglets/guess.zig	Ports stdin/stdout I/O to Zig 0.16 std.Io interfaces.
src/ziglets/factorial.zig	Allocates work ranges dynamically and ports stdout to std.Io.
src/ziglets/clock.zig	Switches to std.Io.Clock and std.Io stdout writer usage.
src/ziglets/calculator.zig	Ports I/O to std.Io and updates raw-mode flag handling.
src/main.zig	Updates help output I/O and changes main signature + args parsing for Zig 0.16.
build.zig	Migrates to module-based addExecutable / addTest wiring for Zig 0.16.