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/docgen/inventory.json

@@ -52,7 +52,12 @@
     "fn-ok",
     "fn-err",
     "fn-is_ok",
-    "fn-is_err"
+    "fn-is_err",
+    "fn-some",
+    "fn-none",
+    "fn-is_some",
+    "fn-is_none",
+    "fn-unwrap_or"
   ],
   "collision": [
     "collision-rects",