Add a minimal TinyGo guest example

[AndyFerns]

Summary

Adds a new Guest example for TinyGo performing simple logging and KV access

Additions

A TinyGo guest (living under the src/ subdir) that exports run and imports host_log_v2 and db_set from the nx namespace.

• Explicit memory boundary handling (converting Go strings to uint32 pointers/lengths).
• Windows (build.bat) and Linux/macOS (build.sh) build scripts.
• A README detailing requirements, build steps, and TinyGo-specific ABI observations.

notes

• used //go:wasmimport and //go:export directives to keep the WASM ABI clean (no C-esque name mangling)
• compiled with -target wasi to prevent TinyGo from injecting JS-specific runtime hooks (which previously caused gojs::runtime.ticks linking errors)
• skipped optimizations (-opt=0) in the build scripts so users don't strictly need wasm-opt (Binaryen) installed on their machines just to run the example.

Closes #51