chore(adr-184): promote wifi-densepose to 2.0.0 stable + ruview 2.0.0 (P2)

ADR-184 P2 (version promotion + changelog) — version-metadata prep only;
triggers NO publish (P3's real PyPI upload is still gated on the manual
Trusted Publisher registration on pypi.org).

- python/pyproject.toml: version 2.0.0a1 -> 2.0.0; classifier
  "Development Status :: 3 - Alpha" -> "5 - Production/Stable".
- python/ruview-meta/pyproject.toml: version 2.0.0a1 -> 2.0.0; same
  classifier bump; repointed the wifi-densepose dependency pins
  (base + [client]) from ==2.0.0a1 to ==2.0.0 so the stable ruview
  meta-package depends on the stable wifi-densepose, not the alpha.
- python/wifi_densepose/__init__.py: runtime __version__ 2.0.0a1 -> 2.0.0
  (caught during the sanity check — it would otherwise contradict the
  stable wheel version reported by `wifi_densepose.__version__`).
- CHANGELOG.md: [Unreleased] entry recording the promotion.

Sanity-checked that the core package genuinely deserves "Production/Stable"
(not just a version-string change):
  maturin build --release --strip  -> default wheel 279 KB
  pytest python/tests/ (excluding [aether]/[meridian]/[mat] extra modules)
    -> 185 passed, 0 failed (smoke/keypoint/pose/vitals/bfld/security/
       WS+MQTT client)
  post-bump: wheel installs as 2.0.0, __version__ = 2.0.0, smoke 6/6 pass.
No publish/tag/release commands were run.

python/pyproject.toml

@@ -10,7 +10,7 @@ build-backend = "maturin"
 
 [project]
 name = "wifi-densepose"
-version = "2.0.0a1"
+version = "2.0.0"
 description = "WiFi-based human pose estimation, vital sign extraction, and ambient intelligence from Channel State Information (CSI). PyO3 bindings for the Rust core."
 readme = "README.md"
 requires-python = ">=3.10"
@@ -23,7 +23,7 @@ keywords = [
     "biometric", "ambient-intelligence", "home-assistant", "matter",
 ]
 classifiers = [
-    "Development Status :: 3 - Alpha",
+    "Development Status :: 5 - Production/Stable",
     "Intended Audience :: Developers",
     "Intended Audience :: Science/Research",
     "License :: OSI Approved :: MIT License",