Test lazy imports in __init__

[keithpeck]

Problem
Importing earthdaily.earthone (or any of its eagerly-loaded sub-packages such as auth) triggered the immediate loading of all sub-packages. The vector sub-package transitively imports geopandas, pandas, and shapely at module level — all of which are expensive to initialise. This caused significant cold-start latency in environments that only need a lightweight sub-package (e.g. a Lambda function using only auth for token management).

Change
All sub-packages except config are now imported lazily using the PEP 562 module-level __getattr__ mechanism. They are loaded on first access rather than at package initialisation time.

config remains eagerly imported as it is required at module load time to assign the top-level select_env and get_settings helpers.

A module-level __dir__ has also been added, returning __all__, so that IDE tab-completion and dir() introspection continue to show lazy sub-packages even before they have been accessed.

Options considered
I considered adding a preload() function to allow opt-in eager loading but doesn't seem to be a common practice. users can achieve the same result with standard Python:

import earthdaily.earthone.catalog
import earthdaily.earthone.compute
import earthdaily.earthone.vector

Adding a named function would expand the public API surface for no meaningful benefit.