HS parser/compiler/mock: fix put positions, add CSS properties

Parser:
- Skip optional "the" in "at the start/end of" put targets
- Handle "style" token type in parse-add-cmd for *prop:value syntax

Compiler:
- Add set-style dispatch → dom-set-style for CSS property additions

Mock DOM:
- Position-aware insertAdjacentHTML: afterbegin prepends, beforeend appends
- Sync textContent after insertAdjacentHTML mutations

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/hyperscript/compiler.sx

@@ -856,6 +856,12 @@
                       (quote dom-add-class)
                       (hs-to-sx raw-tgt)
                       (nth ast 1)))))
+              ((= head (quote set-style))
+                (list
+                  (quote dom-set-style)
+                  (hs-to-sx (nth ast 3))
+                  (nth ast 1)
+                  (nth ast 2)))
               ((= head (quote multi-add-class))
                 (let
                   ((target (hs-to-sx (nth ast 1)))