zig: incremental Zig integration via static lib & unit tests

[evgenykor]

• Scaffold Zig project under zig/ with build.zig producing static lib (libalpakka_zig.a).
• Implement C-ABI function zig_vector_normalize and two tiny Zig tests.
• Add header src/headers/zig_abi.h; delegate vector_normalize() in src/vector.c to Zig.
• Extend CMake to build/link Zig lib (custom target ziglib) into RP2040 firmware.
• Update Makefile clean to remove Zig artifacts (zig/zig-out, zig/.zig-cache).
• Update .gitignore for Zig build outputs.

Build:

• Firmware: DEVICE=alpakka_v1 make succeeds.
• Tests: zig test zig/src/lib.zig pass.

[marcos-diaz]

Ha! great minds think alike!

I had a very similar prototype branch in which I used the same approach (letting pico-sdk/cmake/gcc doing the final linking but incrementally putting everything we do in a zig library).

https://github.com/inputlabs/alpakka_firmware/compare/zig-proto?expand=1

I replaced some of the I2C core functions just to verify it wasn't crashing.

Cmake was a little bit more clean because having compilation parameters and architecture on build.zig

Also doing bidirectional calls by defining some temporal interfaces.

But basically is the same.

[evgenykor]

Cool! So what are your thinking? Do you think it is worth to make such transition? (i.e. to Zig)