lib/ww/lex: tokname if-ladder -> switch (Wave-2 structural)

Fold the ~88-arm `if (k == tkind.TK_X) return "..."` ladder in tokname
to a single `switch (k)` with the terminal `return "<?>"` as the
fall-past default. kwlookup stays an if-ladder: it dispatches on
streqn() string compares over distinct literals, which a value-switch
can't express.

Not byte-id-neutral (if-chain -> switch dispatch changes the asm), so
the ladder->switch equivalence is pinned by a new table-driven test:
lib/ww/lex/toktest.ww drives tokname over every tkind plus the
out-of-band "<?>" fallback, and kwlookup over every keyword plus
non-keywords, wired as 904_tok_run (same `ww run` @test shape as
904_ascii_run). The 990_selfhost wwdump diff only covers kinds that
appear in its corpus.

Regenerates the w6c + wwdump combined.ww amalgamations (tokname region
only).

Makefile

@@ -443,7 +443,7 @@ TESTS	= $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
 	  $(BIN)/test_sort_run \
 	  $(BIN)/test_bufio_run $(BIN)/test_random_run \
 	  $(BIN)/test_asserttyped_gap \
-	  $(BIN)/test_ascii_run
+	  $(BIN)/test_ascii_run $(BIN)/test_tok_run
 
 $(BIN)/test_smoke: test/wcc/000_smoke.c $(LIB)/libwcc.a | $(BIN)
 	$(CC) $(CFLAGS) $(INCS) -o $@ $< -L$(LIB) -lwcc
@@ -1508,6 +1508,10 @@ $(BIN)/test_ascii_run: test/wcc/904_ascii_run.c $(BIN)/ww $(BIN)/w6c \
 		$(BIN)/w6a $(BIN)/w6l $(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
+$(BIN)/test_tok_run: test/wcc/904_tok_run.c $(BIN)/ww $(BIN)/w6c \
+		$(BIN)/w6a $(BIN)/w6l $(LIB)/libwwrt.a | $(BIN)
+	$(CC) $(CFLAGS) -o $@ $<
+
 $(BIN)/test_decimal_run: test/wcc/922_decimal_run.c $(BIN)/ww $(BIN)/w6c \
 		$(BIN)/w6a $(BIN)/w6l $(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<