feat(types): option (some/none) safety type (#53)

Types phase 3 — the option/result safety pair. result/ok/err/try shipped in
#46; this adds its companion option:

- some(v)   -> option   (present value; any i32-width scalar)
- none()    -> option   (empty; no magic -1 sentinel)
- is_some / is_none -> bool
- unwrap_or(o, fallback) -> int

A heap %Option = { i32 present, i32 value }, bare builtins guarded by find_fn
(a user fn of the same name still wins), gated by g_uses_option so unused
programs compile byte-identically — same idiom as result.

Wired: emit_call codegen + %Option decl (emit_decl) + g_uses_option (emit_core),
reseeded seed, vocabulary sync (header/JetBrains/TextMate), builtin docs +
inventory, and a self-asserting example (examples/library/optionresult.ludic +
feat_case). All suites green incl. golden renders byte-identical and the
bootstrap fixpoint.

Tagged-union enums (variant payloads + binding match + exhaustiveness) are the
deep type-system feature, split out to #56.

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

tools/ludic-tools/ludic_syntax.h

@@ -147,6 +147,11 @@ static const LBuiltin LUDIC_BUILTINS[] = {
  {"err","err(msg: string) -> result","Wrap a failure message in a result — the sad half, recovered by `try`/`else`."},
  {"is_ok","is_ok(r: result) -> bool","True when a result carries a success payload."},
  {"is_err","is_err(r: result) -> bool","True when a result carries a failure."},
+ {"some","some(v) -> option","Wrap a present value (any i32-width scalar) in an option — the `has a value` case."},
+ {"none","none() -> option","The empty option — a missing value with no magic -1 sentinel."},
+ {"is_some","is_some(o: option) -> bool","True when an option holds a value."},
+ {"is_none","is_none(o: option) -> bool","True when an option is empty."},
+ {"unwrap_or","unwrap_or(o: option, fallback) -> int","The option's value, or fallback when it is empty."},
  {0,0,0}
 };