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.

R/provenance.R

@@ -6,7 +6,8 @@
                               per_capita, adjust_to_year, result, sql,
                               subtype_col, basis = NA_character_,
                               basis_note = NA_character_,
-                              harmonization = NULL) {
+                              harmonization = NULL, recipe = NULL,
+                              suggestions = list()) {
   manifest <- .uscogdata_env$manifest
 
   codes <- result[["codes_included"]]
@@ -31,6 +32,14 @@
     unique(result$gov_name)
   }
 
+  schema_version <- suppressWarnings(as.integer(manifest$schema_version %||% 0L))
+  con <- .uscogdata_env$con
+  break_refs <- if (!is.null(con) && DBI::dbIsValid(con)) {
+    .build_series_break_refs(con, codes_observed, years, schema_version)
+  } else {
+    character(0)
+  }
+
   list(
     verb = verb,
     call = paste(deparse(call), collapse = " "),
@@ -46,6 +55,8 @@
       applied = FALSE, na_rows_excluded = 0L, na_amount_excluded = 0,
       note = NA_character_
     ),
+    recipe = recipe,
+    suggestions = suggestions,
     scope = list(
       gov_types_included = as.integer(unlist(manifest$scope$gov_types_included)),
       gov_types_excluded = as.integer(unlist(manifest$scope$gov_types_excluded)),
@@ -98,7 +109,7 @@
         index = if (is.null(adjust_to_year)) NA_character_ else "CPI-U (BLS CPIAUCSL annual average, bundled)"
       )
     ),
-    series_break_refs = character(0),
+    series_break_refs = break_refs,
     manifest = list(
       schema_version = as.integer(manifest$schema_version),
       pipeline_commit = manifest$pipeline_commit %||% NA_character_,