compile: no module search-path / project build mode — nested src/** use SiblingModule fails #642

Summary

The core-WASM compile command is single-file only — it has no module search path, so a nested src/** project layout where one module does use SiblingModule fails to resolve ("undefined module"). Downstream, the svalinn gateway (stapeln/container-stack/svalinn/src) cannot be compiled as a project.

Evidence

affinescript compile exposes only [--target TRIPLE] FILE [-o OUT] (bin/main.ml, the compile term is target_arg $ path_arg $ output_arg). There is no --search-path / project / manifest option, and the Module_loader is built from defaults, so a use SiblingModule referencing another file under src/ relative to the entry file is not found.

Suggested direction

Either:

• a repeatable --search-path DIR flag threaded into the Module_loader config used by compile, or
• a project/manifest build mode (compile a directory / a manifest) that roots module search at the project src/.

Context

Surfaced while characterising svalinn-gateway compiler gaps after the cross-module constructor-link fix (#138 / #602, ac98c81). This is a separate gap — module resolution at compile time, not constructor codegen. Confirmed at main b8ba479.