feat(selfhost-checker): add RS0014/RS0018/RS0019 (runtime-guarantee bodies)

Wire the runtime-guarantee body probes into the gate:
- RS0014: an effects(noalloc) fn that constructs a value (unqualified call
  to a declared type) or uses `manage`.
- RS0018 / RS0019: an effects(no_block) / effects(no_panic) fn making an
  unqualified call to a user function that does not carry the same
  guarantee (constructors, enum variants, and same-guarantee callees are
  allowed). Mirrors check_runtime_guarantee_*; the qualified-stdlib-call
  cases have no corpus fixtures.

Corpus checker_parity_corpus: 619/619 byte-exact, 0 mismatches.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: olwang

crates/rsscript/src/selfhost_parity.rs

@@ -503,7 +503,7 @@ fn parser_parity_corpus() {
 // ---------------------------------------------------------------------------
 
 /// Diagnostic codes the rss checker is expected to reproduce.
-const CHECKER_TARGET_CODES: &[&str] = &["RS0002","RS0003","RS0004","RS0005","RS0006","RS0007","RS0008","RS0009","RS0010","RS0011","RS0012","RS0016","RS0017","RS0021","RS0024","RS0028","RS0033","RS0029","RS0023","RS0035","RS0027"];
+const CHECKER_TARGET_CODES: &[&str] = &["RS0002","RS0003","RS0004","RS0005","RS0006","RS0007","RS0008","RS0009","RS0010","RS0011","RS0012","RS0016","RS0017","RS0021","RS0024","RS0028","RS0033","RS0029","RS0023","RS0035","RS0027","RS0014","RS0018","RS0019"];
 
 fn is_target_code(code: &str) -> bool {
     CHECKER_TARGET_CODES.contains(&code)