Add granular Elixir library and binary targets

Elixir projects can now define [[elixir.library]] and [[elixir.binary]] targets. Each target produces a per-target .ebin directory of .beam files, and binary targets emit a launcher script that resolves the workspace root at runtime. Compiles are routed through a daemon-aware wrapper that can use a long-lived BEAM compile daemon when available, with identical arguments so caching works the same whether the daemon is running or not. Start the daemon with fabrik elixir-daemon start and check health with fabrik elixir-daemon status.