Silent-by-default script loaders

Date: 2026-05-04 Area: runtime Pull Request: #510

Script loaders are silent-by-default about the script's last evaluated value, mirroring node script.js / bun script.js / deno run script.js / qjs script.js. Printing is opt-in via --print (or "print": true in goccia.json for GocciaScriptLoader), which emits the bare value on its own line including undefined — the same semantics as node -p / bun --print / deno eval -p. Replaces the previous "always print Result: <value> banner" behavior, which was the outlier among mainstream JS runtimes and surfaced as a false-positive vector in substring-graded environments such as test262.fyi (#509). GocciaScriptLoader's human-readable timing banner ("Running script (interpreted): ..." + Lex/Parse/Execute line) is unchanged; only the final value line moved behind the flag. JSON output (--output=json) still always carries the result in the structured result field regardless of --print. build-system.md § Compile and Run.