feat: cog_recipes + recipe= + signposting suggestions

Adds cog_recipes() to list the curated harmonization_recipes catalog (24
recipes / schema_version >= 5), and a recipe= argument on cog_spending()/
cog_revenue() that runs a recipe's generic multi-code join instead of the
category view: SUM(amt * weight) across whichever component codes are
present for a (year, canonical_govid), scoped by gov_type_scope. The join
deliberately does not filter is_aggregate -- the wide era (<= 2011) exposes
these split families (corrections 04+05, IG *89/*47, U4- rents, etc.) ONLY
as aggregate rows, with leaf codes first appearing in 2012, so excluding
aggregates would zero out the wide-era half of every recipe. This is safe
by corpus construction: wide-era rows are aggregate-only, modern rows are
leaf-only, and every component is year-scoped, so there is no
double-counting. recipe= is mutually exclusive with category=; the result's
subtype column reads "recipe" and category reads the recipe's label.

Adds recipe-component-driven signposting: when a basis="harmonized" +
category query comes back with zero rows in a requested year, and a
harmonization recipe covering that category would actually produce rows
for this government in that year (via the same join .run_recipe() uses),
the recipe is surfaced in provenance$suggestions plus one
cli::cli_inform() message. This is deliberately keyed off recipe
components rather than harmonization_map's suggested_recipe_id column
(which is empty on every live row -- the wide era's split families are
NA-by-construction via aggregate exclusion, not an NA ruling to hang a
suggestion off of).

Also populates the previously-always-empty provenance$series_break_refs
(schema v5 only: series_breaks_pq rows whose fin_code is among the
observed codes and whose break_year falls in the requested span), and
extends cog_explain() with Basis/Harmonization/Recipe/Suggestions/Series
breaks sections.

tests/testthat/test-views.R

@@ -51,6 +51,29 @@ test_that("the REPLACE(harmonized_code AS item_code) pattern folds a collapsed c
   DBI::dbExecute(con, "DROP TABLE synthetic_long")
 })
 
+test_that(".build_series_break_refs matches fin_code + break_year window", {
+  # No series_breaks_pq row falls inside the bundled fixture's 2011-2020
+  # window (data-verified; see the "series_break_refs" test in
+  # test-spending.R), so this proves the matching logic itself against the
+  # live view + a synthetic year window that DOES hit a cataloged break
+  # (SB075, fin_code E62, break_year 2005).
+  skip_if_no_corpus()
+  con <- cog_open()
+  on.exit(cog_close())
+  refs <- uscogdata:::.build_series_break_refs(
+    con, codes_observed = c("E62", "E04"), years = c(2003L, 2006L),
+    schema_version = 5L
+  )
+  expect_true("SB075" %in% refs)
+  expect_true("SB071" %in% refs)
+
+  # Gated on schema_version >= 5 even when the codes/years would otherwise match.
+  refs_v4 <- uscogdata:::.build_series_break_refs(
+    con, codes_observed = c("E62"), years = c(2003L, 2006L), schema_version = 4L
+  )
+  expect_equal(refs_v4, character(0))
+})
+
 test_that("schema v5 harmonization views register when the corpus supports them", {
   skip_if_no_corpus()
   con <- cog_open()