Remove function cache and artifact cache

[aqk]

Note

Medium Risk
Touches core codegen and module compile paths; behavior should match a cold compile but compile time and I/O patterns change, with no remaining cache invalidation edge cases.

Overview
Removes two compile caches so compilation always does full codegen and file output instead of reusing prior results.

In-memory Funcache is deleted: FunctionEntry, get_function_cache_key, env filtering helpers, and the dependency_graph parameter on codegen / codegen_. Out-of-line defun bodies are always generated and no longer looked up or stored in BasicCompileContext. The deinline pass still builds a dependency graph for module-phase helper pruning but no longer seeds or passes a cache into codegen.

On-disk module cache is removed entirely: the diskcache module, try_from_cache / get_hex_name_of_export, and set_cache_element calls when writing export hex. Module compilation in compile_pre_forms no longer short-circuits on .chialisp/<key>/ hits.

Tests for both mechanisms (codegen_funcache, module_cache, cache reuse in modules.rs) and test-only FS helpers are dropped accordingly.

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[prozacchiwawa]

thanks