fix(wqp): repair WQP_Metadata.site_info (was always None)

[thodson-usgs]

Problem

WQP_Metadata.site_info never returned anything — it was always None, for every query. Two compounding bugs:

1. The call sites passed no parameters. All nine WQP getters built WQP_Metadata(response) (no **kwargs), so self._parameters was always {} and the property always fell through to else: return None. NWIS does it correctly — NWIS_Metadata(response, **kwargs). (PR fix: repair WQP_Metadata.site_info and streamstats.Watershed #295 fixed the property's location — it had been a discarded local function nested in __init__ — but the call sites still dropped the params, so the feature remained dead; that PR's test even asserted site_info is None, which masked it.)

2. The property keyed on the wrong parameter. It checked sites/site/site_no and called what_sites(sites=...), but WQP's site identifier is siteid (per the docstring and tests, e.g. get_results(siteid="WIDNR_WQX-10032762")). So even with params threaded through, it could never match a real WQP query.

Fix

• All getters now pass the query kwargs: WQP_Metadata(response, **kwargs).
• site_info keys on siteid and calls what_sites(siteid=...).
• Corrected the class docstring (comment not comments; WQP_Metadata not NWIS_Metadata; siteid not sites).

Verification

• Live API: df, md = what_sites(siteid="WIDNR_WQX-10032762") → md._parameters now carries siteid, and md.site_info returns a populated (DataFrame, WQP_Metadata) tuple (previously None).
• Tests: updated the routing test to the correct siteid key; added a regression assertion that get_results threads siteid into the metadata. All 14 wqp tests pass; ruff clean.

Note: accessing md.site_info issues a live what_sites request (by design) and carries that call's legacy/WQX3 warning.

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