Phase 5 cleanup: remove legacy HTML components, fix nav-tree fragment

- Remove old raw! layout components (~app-head, ~app-layout, ~oob-response,
  ~header-row, ~menu-row, ~oob-header, ~header-child) from layout.sexp
- Convert nav-tree fragment from Jinja HTML to sexp source, fixing the
  "Unexpected character: ." parse error caused by HTML leaking into sexp
- Add _as_sexp() helper to safely coerce HTML fragments to ~rich-text
- Fix federation/sexp/search.sexpr extra closing paren
- Remove dead _html() wrappers from blog and account sexp_components
- Remove stale render import from cart sexp_components
- Add dev_watcher.py to auto-reload on .sexp/.sexpr/.js/.css changes
- Add test_parse_all.py to parse-check all 59 sexpr/sexp files
- Fix test assertions for sx- attribute prefix (was hx-)
- Add sexp.js version logging for cache debugging

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

test/entrypoint.sh

@@ -16,6 +16,7 @@ fi
 RELOAD_FLAG=""
 if [[ "${RELOAD:-}" == "true" ]]; then
   RELOAD_FLAG="--reload"
+  python3 -m shared.dev_watcher &
 fi
 PYTHONUNBUFFERED=1 exec hypercorn "${APP_MODULE:-app:app}" \
   --bind 0.0.0.0:${PORT:-8000} \