helwasm: store-on-correct, store button reflects existence, use stored spec

- new read-only export hel_entry(name): the entry's canonical stored form, or ""
- Mark correct now also stores the name (keeps the entry); unmark keeps the stored
  name and just drops the hash (wraps add/rm for an ephemeral entry so the right
  hash is removed)
- Store button shows "Stored ✓" (disabled, ocean outline) when the name is already
  in the catalog, "Store" otherwise
- when a typed name already exists, the field adopts the full stored spec on blur
  (real mode/seq/date/parent) instead of a default-extended parse

helwasm/style.css

@@ -185,6 +185,9 @@ input.mask.revealed { -webkit-text-security: none; }
 .btn.small.is-correct { background: var(--ocean); color: var(--cream); border-color: var(--ocean); }
 .btn.small.is-correct:hover { background: var(--deep); border-color: var(--deep); }
 .btn:disabled { opacity: .4; cursor: not-allowed; pointer-events: none; }
+/* "Stored ✓": not an action (disabled), but shown as a confirmed ocean outline
+   rather than the dimmed disabled look. */
+.btn.small.is-stored { opacity: 1; background: transparent; color: var(--ocean); border-color: var(--ocean); }
 
 /* Quick-gen result row */
 .result {