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

man/cog_revenue.Rd

@@ -12,6 +12,7 @@ cog_revenue(
   adjust_to_year = NULL,
   basis = c("harmonized", "raw"),
   recipe = NULL,
+  revenue_concept = c("general", "total"),
   complete = FALSE
 )
 }
@@ -57,6 +58,32 @@ argument is ignored and the result's provenance reports
 FALSE`, pointing at the `recipe` block instead) rather than a
 possibly-misleading `"harmonized"`/`"raw"` value.}
 
+\item{revenue_concept}{Which of Census's two published revenue concepts to
+  return. Concepts are defined as sets of the crosswalk's `revenue_subtype`
+  values -- never as item-code first letters, which cannot classify
+  correctly (prefix `Y` spans revenue, expenditure and balance codes, and
+  prefix `X` does the same):
+
+  * `"general"` (default) -- Census General Revenue: `own_source` +
+    `federal` + `state` + `local_aid`. The manual defines this concept by
+    subtraction (section 4.3: *"General revenue comprises all revenue
+    except that classified as liquor store, utility, or insurance trust
+    revenue"*), so utility (`A91`-`A94`), liquor store (`A90`) and
+    insurance trust revenue are all excluded.
+  * `"total"` -- Census Total Revenue: every revenue subtype, i.e.
+    `general` plus utility, liquor store, and insurance trust revenue
+    (`Y01`/`Y02`/`Y04`/`Y11`/`Y12`/`Y51`/`Y52` and the employee-retirement
+    `X01`/`X02`/`X05`/`X08`).
+
+  The two are related by Census's own identity, `Total Revenue = General +
+  Utility + Liquor Store + Insurance Trust`.
+
+  Note that the employee-retirement (`X`) codes stop at FY2016, when those
+  systems moved out of the annual finance file into the separate Annual
+  Survey of Public Pensions, so a `"total"` series steps down at the
+  FY2016/FY2017 seam for reasons that are about collection scope rather
+  than revenue (series breaks `SB197`-`SB202`).}
+
 \item{complete}{If `TRUE`, fill the requested grid so that a cell the
   corpus does not carry still appears, labelled with **why** it is
   missing, and add a `value_source` column to every row: