feat: determine AffixType as early as possible

`affix()` is more robust thant `henkanFirst()` because
`affix()` is `state.type`-aware.

`henkanFirst()` may determine AffixType if it is undefined.
However, the result might be wrong because prefix has higher priority
than suffix.

denops/skkeleton/function/henkan.ts

@@ -37,7 +37,14 @@ export async function henkanFirst(context: Context, key: string) {
     ? state.henkanFeed
     : getOkuriStr(state.henkanFeed, state.okuriFeed);
   state.word = word;
-  if (!state.directInput && ["okurinasi", "okuriari"].includes(state.mode)) {
+  if (
+    state.affix == null &&
+    !state.directInput &&
+    ["okurinasi", "okuriari"].includes(state.mode)
+  ) {
+    // When user maunally uses henkanPoint,
+    // henkanFeed like `>prefix` and `suffix>` may
+    // reach here without undetermined affix
     state.affix = state.henkanFeed.match(">$")
       ? "prefix"
       : state.henkanFeed.match("^>")

denops/skkeleton/function/input.ts

@@ -197,6 +197,7 @@ export async function affix(context: Context, key: string) {
     ["okurinasi", "okuriari"].includes(context.state.mode)
   ) {
     await acceptResult(context, [">", ""], "");
+    context.state.affix = "prefix";
     await henkanFirst(context, key);
     return;
   }
@@ -206,6 +207,7 @@ export async function affix(context: Context, key: string) {
     await kakutei(context);
     henkanPoint(context);
     await acceptResult(context, [">", ""], "");
+    context.state.affix = "suffix";
     return;
   }