HS: E37 tokenizer API (+17 tests)

Implements hs-tokens-of, hs-stream-token, hs-stream-consume,
hs-stream-has-more, hs-token-type, hs-token-value, hs-token-op?,
hs-raw->api-token, hs-eof-sentinel in runtime.sx.

Tokenizer emits whitespace tokens after the first content token;
stream functions skip them for look-ahead and consume. Parser
filters whitespace tokens at hs-parse entry. Dot/hash after close
brackets split into PERIOD/POUND + IDENTIFIER. Template escape \$
produces literal $.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/hyperscript/tokenizer.sx

@@ -465,7 +465,12 @@
         scan!
         (fn
           ()
-          (skip-ws!)
+          (let
+            ((ws-start pos))
+            (skip-ws!)
+            (when
+              (and (> (len tokens) 0) (> pos ws-start))
+              (hs-emit! "whitespace" (slice src ws-start pos) ws-start)))
           (when
             (< pos src-len)
             (let
@@ -489,6 +494,15 @@
                 (do (hs-emit! "selector" (read-selector) start) (scan!))
                 (and (= ch ".") (< (+ pos 1) src-len) (= (hs-peek 1) "."))
                 (do (hs-emit! "op" ".." start) (hs-advance! 2) (scan!))
+                (and
+                  (= ch ".")
+                  (< (+ pos 1) src-len)
+                  (or (hs-letter? (hs-peek 1)) (= (hs-peek 1) "-") (= (hs-peek 1) "_"))
+                  (> (len tokens) 0)
+                  (let
+                    ((lt (dict-get (nth tokens (- (len tokens) 1)) :type)))
+                    (or (= lt "paren-close") (= lt "brace-close") (= lt "bracket-close"))))
+                (do (hs-emit! "dot" "." start) (hs-advance! 1) (scan!))
                 (and
                   (= ch ".")
                   (< (+ pos 1) src-len)
@@ -500,6 +514,15 @@
                   (hs-advance! 1)
                   (hs-emit! "class" (read-class-name pos) start)
                   (scan!))
+                (and
+                  (= ch "#")
+                  (< (+ pos 1) src-len)
+                  (hs-ident-start? (hs-peek 1))
+                  (> (len tokens) 0)
+                  (let
+                    ((lt (dict-get (nth tokens (- (len tokens) 1)) :type)))
+                    (or (= lt "paren-close") (= lt "brace-close") (= lt "bracket-close"))))
+                (do (hs-emit! "op" "#" start) (hs-advance! 1) (scan!))
                 (and
                   (= ch "#")
                   (< (+ pos 1) src-len)