Wire deps.sx into both bootstrappers, rebootstrap Python + JS

deps.sx is now a spec module that both bootstrap_py.py and bootstrap_js.py
can include via --spec-modules deps. Platform functions (component-deps,
component-set-deps!, component-css-classes, env-components, regex-find-all,
scan-css-classes) implemented natively in both Python and JS.

- Fix deps.sx: env-get-or → env-get, extract nested define to top-level
- bootstrap_py.py: SPEC_MODULES, PLATFORM_DEPS_PY, mangle entries, CLI arg
- bootstrap_js.py: SPEC_MODULES, PLATFORM_DEPS_JS, mangle entries, CLI arg
- Regenerate sx_ref.py and sx-ref.js with deps module
- deps.py: thin dispatcher (SX_USE_REF=1 → bootstrapped, else fallback)
- scan_components_from_sx now returns ~prefixed names (consistent with spec)

Verified: 541 Python tests pass, JS deps tested with Node.js, both code
paths (fallback + bootstrapped) produce identical results.

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

shared/sx/tests/test_deps.py

@@ -147,7 +147,7 @@ class TestScanComponentsFromSx:
     def test_basic(self):
         source = '(~card :title "hi" (~badge :label "new"))'
         refs = scan_components_from_sx(source)
-        assert refs == {"card", "badge"}
+        assert refs == {"~card", "~badge"}
 
     def test_no_components(self):
         source = '(div :class "p-4" (p "hello"))'