feat(js): expose typed browser environment and object-prop helpers

[GG-O-BP]

Summary

Implements #9. Adds a typed public capability so Mendix widgets can read the
browser color-scheme preference and pass a single plain-object React prop
without any application-local FFI.

• New glendix/js/environment module:
  • ColorScheme { Light, Dark, System } — the OS preference (System when
    none is expressed or matchMedia is unavailable).
  • ResolvedColorScheme { ResolvedLight, ResolvedDark, ResolutionUnavailable }
    — what actually applies, distinguishing an unavailable environment from a
    resolved light preference.
  • matchMedia stays hidden behind the FFI; dynamic preference-change
    subscriptions are intentionally documented as out of scope.
• Hardened glendix/js/object.from_entries to use Object.fromEntries, so
  ordered typed entries preserve key order, keep the last value for duplicate
  keys, and store special keys such as __proto__ as own data.
• Documented the browser-environment + single-object-prop pattern (via
  object.from_entries → binding.element) in README and guide (EN/KO/JA).

Acceptance mapping

• ✅ Query color-scheme preference without exposing matchMedia.
• ✅ Represent light/dark/system explicitly.
• ✅ Build a plain object from ordered typed entries (order preserved,
  duplicate/empty/__proto__ handled safely).
• ✅ Pass the object as one external-component prop through Glendix bindings.
• ✅ Existing DOM/object APIs remain compatible.

Tests

Contract tests cover light, dark, system-resolved, and unavailable
preferences; entry order, empty, duplicate-key, and prototype-key object
construction; and object-prop pass-through via binding.element.

Verification

• ./scripts/verify.sh inner glendix — pass (28 tests).
• check-all — pass (format, compile, warnings-as-errors, docs, FFI export
  contracts for 318 externals, repository boundaries).
• ./scripts/family.sh widget-build — pass (glendix → .mpk).
• Family unit suites — pass (glendix 28, mendraw 41, mxpak 121, glendam 61).
• Dependency-source gate (dependency-mode check-commit glendix) — valid;
  flexible glendix→mendraw edge left unchanged (hex).

Note: the mandatory verify.sh final push gate could not complete in the
current environment — test-all is blocked by a transient Hex API rate limit
(mxpak standalone-consumer download, an untouched package), and the Mendix
full E2E / Lustre E2E require Mendix DB/runtime, the secret token, and a live
browser session that are not runnable here. Mendix/Lustre compatibility is
therefore not claimed and should be confirmed by CI or a maintainer before
release.

Closes #9