feat: revenue_concept = c("general", "total") off the crosswalk (#12)

Closes the last blocked test in the suite. Owner ruled both halves of the
open question yes on 2026-07-30.

`cog_revenue()` gains `revenue_concept`, mirroring `expenditure_concept`,
with Census's two published concepts defined as crosswalk
`revenue_subtype` sets rather than item-code prefixes:

  general = own_source + federal + state + local_aid   (the default)
  total   = general + utility + liquor_store + insurance_trust

The manual defines the first by subtracting the other three from the
second (4.3), so both are computable only once all four families are
named -- which cog_pipeline#79 does. Insurance trust now includes the
employee-retirement X codes (X01/X02/X05/X08) alongside the Y codes.

- inst/sql: revenue_long / revenue_long_harmonized carry EVERY revenue
  subtype; the concept narrows in R via the existing subtype_scope
  machinery, exactly as expenditure_concept narrows spending_long.
- cog_explain() now prints each verb's OWN concept. It previously
  printed `expenditure_concept` unconditionally, so a cog_revenue()
  caller was told "Concept: primary" -- a spending concept their result
  has nothing to do with.
- Fixture regenerated at pipeline_commit aadb46b (330 crosswalk rows).

Corrected two stale expectations in the blocked test while un-skipping
it. It asserted X01+X04+X05+X08 and omitted X02, which applies to state
governments and is nonzero for Wisconsin; X04 is an exhibit code for an
INTRAgovernmental transfer that Census's own "Total Emp Ret Rev"
excludes. Verified against that Census field: the right set is
X01+X02+X05+X08 = $2,283,883k, exactly. And its expected `total` of
$33,377,093k predated the Y codes being classified -- complete Total
Revenue for WI FY2012 is $34,881,961k (general 31,338,293 + Y 1,259,785
+ X 2,283,883).

Behaviour change worth knowing: `general` is now STRICT Census General
Revenue, so utility and liquor store revenue leave the default. Measured
on the fixture that is 15.9% of what cog_revenue() returned for cities,
vs 1.2% for states and 1.7% for counties.

Suite: 716 pass / 0 fail / 0 skip -- the first time this package has had
no skipped tests.

Closes #12

R/explain.R

@@ -60,7 +60,15 @@ cog_explain <- function(result, format = c("print", "list")) {
     cli::cli_text("Basis: {prov$basis}{note}")
   }
 
-  if (!is.null(prov$expenditure_concept)) {
+  # Each verb reports its OWN concept. Both fields are always present (each
+  # defaults to its concept's default), so printing `expenditure_concept`
+  # unconditionally would tell a cog_revenue() caller "Concept: primary",
+  # which names a spending concept their result has nothing to do with.
+  if (identical(prov$verb, "cog_revenue")) {
+    if (!is.null(prov$revenue_concept)) {
+      cli::cli_text("Concept: {prov$revenue_concept} revenue")
+    }
+  } else if (!is.null(prov$expenditure_concept)) {
     concept_note <- if (!is.null(prov$expenditure_concept_note) &&
                          !is.na(prov$expenditure_concept_note)) {
       sprintf(" (%s)", prov$expenditure_concept_note)