Switch WQP default profile from legacy to WQX3.0

[thodson-usgs]

Closes #121

Summary

• Changed all WQP function signatures from legacy=True to legacy=False
• get_results, what_sites, and what_activities now route to WQX3.0 endpoints by default
• Functions without a WQX3.0 equivalent (what_organizations, what_projects, what_detection_limits, what_habitat_metrics, what_project_weights, what_activity_metrics) emit a UserWarning when called with the default legacy=False, making it clear the user is getting legacy data
• legacy=True still works but triggers a DeprecationWarning directing users to remove it
• Removed the now-unnecessary _warn_wqx3_use() function (WQX3.0 is no longer experimental)

Behavior change demo (live API)

from dataretrieval.wqp import get_results

# Default: now hits the WQX3.0 endpoint
df, md = get_results(siteid="USGS-01646500", startDateLo="01-01-2024", startDateHi="03-01-2024")
print(md.url)
# https://www.waterqualitydata.us/wqx3/Result/search?siteid=USGS-01646500&...

# Explicit legacy=True still works, with a DeprecationWarning:
df, md = get_results(legacy=True, siteid="USGS-01646500", startDateLo="01-01-2024", startDateHi="03-01-2024")
# DeprecationWarning: ... Setting `legacy=False` will remove this warning.
print(md.url)
# https://www.waterqualitydata.us/data/Result/Search?siteid=USGS-01646500&...

Test plan

• Updated test_what_sites and test_what_activities to mock WQX3.0 URLs
• Added test_get_results_legacy to verify legacy=True triggers DeprecationWarning
• Live verification: default get_results call routes to /wqx3/Result/search and returns data; legacy=True routes to /data/Result/Search and emits the expected DeprecationWarning.
• All unit tests pass

[thodson-usgs]

Closing this PR after auditing the R dataRetrieval package's current stance — we're moving in the opposite direction from upstream.

R's position (verified against the local clone)

R defaults all WQP functions to legacy and treats WQX3 as opt-in beta:

• R/readWQPdata.R:250 — service = "Result" (legacy) is the default; WQX3 routes are ResultWQX3 / StationWQX3 / ActivityWQX3, opt-in via service="...".
• R/AAA.R:46-53 — two messaging functions:
  • wqp_message() (fires on legacy): "NEWS: Data does not include USGS data newer than March 11, 2024. More details: https://doi-usgs.github.io/dataRetrieval/articles/Status.html"
  • wqp_message_beta() (fires on WQX3): "WQX3 services are in-development, use with caution."
• vignettes/Status.Rmd:115 makes the policy explicit:

  "dataRetrieval WQP functions continue to default to the legacy system... The new replacement services aren't currently set as the default because the WQP team still considers these services 'beta', and therefore performance is not guaranteed."

What this PR proposed vs. what R does

	this PR	R
Default profile	WQX3	legacy
legacy=True notice	DeprecationWarning	message() (legacy is not deprecated)
legacy=False notice	(removed)	message() ("still in development")
Frames WQX3 as	"no longer experimental"	"still considers these services 'beta'"

The "WQX3 is no longer experimental" claim is inconsistent with what the R team — and per them, the WQP team itself — currently believe.

Recommendation

Hold off on flipping the default until the WQP team marks WQX3 GA. R will likely flip first; we mirror them when it happens. Meanwhile, main's current behavior (default legacy=True, both warnings fire) is already roughly aligned.

Possible small follow-up (separate)

main's _warn_legacy_use() uses DeprecationWarning and tells users "Setting legacy=False will remove this warning" — that's stronger than R's plain message() and pushes users toward beta services. Worth softening to UserWarning and rewording to match R's "data is stale since 2024-03-11" framing. Tracking this as a possible separate PR; not opening one yet pending direction.