feat: basis= harmonized/raw with v4/v5 dual-accept

Adds schema_version 5 support alongside the existing v4 corpus:
.validate_schema() now accepts a supported set (4, 5) instead of a single
expected version, and cog_spending()/cog_revenue() gain basis =
c("harmonized", "raw"). Harmonized basis routes to new
spending_annotated_harmonized / revenue_annotated_harmonized views built on
spending_long_harmonized / revenue_long_harmonized (REPLACE(harmonized_code
AS item_code), excluding aggregate and NA-harmonized rows); raw basis is
byte-identical to the pre-Phase-R2 behavior. On a v4 corpus, an unspecified
basis silently resolves to "raw" with a provenance note; an explicit
basis = "harmonized" aborts with an actionable message.

Provenance gains basis, basis_note, and a harmonization block
(applied/na_rows_excluded/na_amount_excluded). The five new schema-v5-only
SQL views (harmonized long/annotated views, harmonization_map,
harmonization_recipes, series_breaks_pq) are registered conditionally on
manifest$schema_version >= 5, since DuckDB's read_parquet() errors eagerly
at CREATE VIEW time when the backing file doesn't exist on a v4 corpus.

Fixture corpus regenerated to schema_version 5 / years 2011, 2012, 2019,
2020 (2011->2012 spans the wide-aggregate -> modern-leaf format boundary
needed for the harmonization/recipe work), with the harmonization_map /
harmonization_recipes / series_breaks parquet tables bundled alongside the
existing metadata registries.

tests/testthat/helper-fixture.R

@@ -26,3 +26,34 @@ with_fixture_corpus <- function(code) {
   }, add = TRUE)
   force(code)
 }
+
+# Copy the bundled fixture to a temp dir with manifest.json's schema_version
+# patched to `version`, then run `code` against it with a clean session
+# (mirrors with_fixture_corpus()). Used to exercise the v4/v5 dual-accept
+# path without a second physical fixture tree: a real v4 corpus has no
+# harmonization_map/harmonization_recipes/series_breaks parquet files, but
+# .register_views() only *reads* those when schema_version >= 5 (see
+# R/views.R), so a doctored copy of the (v5) bundled fixture with the
+# manifest's schema_version knocked down to 4 is a faithful stand-in.
+with_doctored_schema_version <- function(version, code) {
+  src <- fixture_corpus_path()
+  tmp <- withr::local_tempdir(.local_envir = parent.frame())
+  file.copy(list.files(src, full.names = TRUE), tmp, recursive = TRUE)
+
+  manifest_path <- file.path(tmp, "manifest.json")
+  m <- jsonlite::fromJSON(manifest_path, simplifyVector = FALSE)
+  m$schema_version <- as.integer(version)
+  writeLines(
+    jsonlite::toJSON(m, auto_unbox = TRUE, pretty = TRUE, null = "null"),
+    manifest_path
+  )
+
+  old_url <- Sys.getenv("USCOGDATA_URL", unset = NA)
+  uscogdata:::cog_close()
+  Sys.setenv(USCOGDATA_URL = paste0(tmp, "/"))
+  on.exit({
+    uscogdata:::cog_close()
+    if (is.na(old_url)) Sys.unsetenv("USCOGDATA_URL") else Sys.setenv(USCOGDATA_URL = old_url)
+  }, add = TRUE)
+  force(code)
+}