fix: add wifi_densepose package for correct module import (#314)

The README Quick Start tells users to `pip install wifi-densepose` and then
`from wifi_densepose import WiFiDensePose`, but no `wifi_densepose` Python
package existed — only `v1/src`. This adds a top-level `wifi_densepose/`
package with a WiFiDensePose facade class matching the documented API, and
updates pyproject.toml to include it in the distribution.

Closes #314

pyproject.toml

@@ -185,7 +185,7 @@ package-dir = {"" = "."}
 
 [tool.setuptools.packages.find]
 where = ["."]
-include = ["src*"]
+include = ["wifi_densepose*", "src*"]
 exclude = ["tests*", "docs*", "scripts*"]
 
 [tool.setuptools.package-data]