docs: roxygen, NEWS, and pkgdown for basket mode

Adds full @description, @details (algorithm), @examples on
cog_gov_search(); examples on cog_basket_resolution() /
cog_basket_unresolved(); NEWS.md entry covering the new mode and
the pattern->name rename; pkgdown reference entries for the two
new exports.

NEWS.md

@@ -0,0 +1,21 @@
+# uscogdata 0.1.0 (development)
+
+## New features
+
+* `cog_gov_search()` gains a **basket mode**: passing vector `name`
+  / `state` / `type` arguments resolves multiple place names in one
+  call and returns a tibble of canonical rows in input order, ready
+  to pipe into `cog_spending()` / `cog_revenue()`. Per-row resolution
+  follows an exact-then-substring matching algorithm with deterministic
+  disambiguation; ambiguous and missing entries are surfaced via a
+  sidecar audit tibble plus a single console summary message.
+* New exports `cog_basket_resolution()` and `cog_basket_unresolved()`
+  expose the basket sidecar for iterative query refinement.
+
+## Breaking changes
+
+* The first formal of `cog_gov_search()` was renamed from `pattern`
+  to `name`. All existing call sites in `cog_explorer/` and the
+  package itself use positional first-arg, so this rename is
+  non-breaking in practice. Callers that pass `pattern = ...` by name
+  must update to `name = ...`.