Function compile_app 

pub fn compile_app(
    dir: &Path,
    parser: &dyn SourceParser,
    plugins: &dyn CompilerPlugins,
    deps: &CompileDeps,
    warnings: &mut Vec<String>,
) -> Result<CompiledApp, RunError>

Ahead-of-time compile an app directory into a lumen_ir::artifact::CompiledApp: parse markup + CSS once, run the full cascade, resolve asset / include / import paths, and bake the combined script source. The returned artifact is what lumenc build writes to disk and what a parser-free runtime loads via RunOptions::artifact.

This is the AOT counterpart to [load_ir]: same front-end work, on the same discovered page set, but the result is serialized instead of spawned. A multi-page app compiles whole - every page assembled into the one gated tree the run path builds, plus the page set the routing needs. Requires the source parser (runtime-parse feature).

What a script compiler warned about is added to warnings, one line each, for the caller to print where it prints its own warnings.