[norbot7865]

Summary

Addresses the requested brepl validation from issue #15:

• adds bounded Clojure-compatible music.core/load-file evaluation
• runs loaded top-level forms sequentially inside the caller's existing serialized/session namespace context
• limits editor-requested files to 16 MiB
• adds raw nREPL coverage matching brepl's eval request containing (load-file "...")
• documents actual brepl v2.7.1/Babashka v1.12.218 validation, port discovery behavior, and commands
• links brepl from the README nREPL overview

Actual brepl validation

Against lgs repl --no-audio --nrepl 0:

• .nrepl-port discovery: pass
• brepl -e '(+ 1 2 3)': 6
• stdout plus value response: hello-from-brepl, then 42
• raw verbose describe: pass, expected operations returned
• brepl -f out/brepl-controls.lg: pass; sequential defsynth, ctl, and ramp evaluated, returning the ramp handle
• unknown function: structured let-go error and brepl exit code 2

The initial validation identified that brepl's -f uses eval of the load-file function rather than the standard nREPL load-file op; this PR closes that compatibility gap.

Automated validation

• make test-nrepl
• go test ./...
• go test -race ./internal/lisp ./internal/nrepl

Refs #15.