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/x/test.ludic

@@ -196,6 +196,7 @@ function cmd_test() -> int {
   feat_case("library/bignum", "", "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16", "bignum.ludic (BigInt arbitrary-precision + Decimal exact base-10 money)")
   feat_case("library/containers", "", "1 2 3 4 5 6 7 8 9 10 11 12 13 14", "containers.ludic (Dict string-keyed hash map + Set string set)")
   feat_case("library/numeric", "", "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20", "numeric.ludic (Huge idle big-numbers + Angle wrapping radians + Percent clamped [0,1])")
+  feat_case("library/optionresult", "", "1 2 3 4 5 6 7 8 9 10 11 12", "optionresult.ludic (option some/none + result ok/err/try safety types)")
   feat_case("library/regex", "", "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18", "regex.ludic (Regex match/find/groups/classes/quantifiers/replace + linear-time safety)")
   feat_case("library/grid", "", "1 2 3 4 5 6 7 8 9 10 11 12 13", "grid.ludic (Grid line/flood/line_of_sight + A* pathfinding over the tilemap)")
   feat_case("library/anim", "", "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34", "anim.ludic (Anim frame/once/pingpong/cell + Tween progress/loop/yoyo/ease/number/round/point/tint)")