fix: govid input ergonomics + clearer missing-govid message

Two UX fixes surfaced by first real-user use:

1. cog_spending / cog_revenue / cog_geographic_rollup now accept either
   a character vector OR a data.frame with a canonical_govid column
   (e.g. output of cog_gov_search() or cog_find_peers()). Shared
   .coerce_govid_input() helper in session.R. This lets the natural
   pipe work:

     cog_gov_search('MIAMI', state='FL', type='city') |>
       cog_spending(years=2022, category='Police')

   cog_peer_compare already accepted a data.frame for the peer arg;
   behavior there is unchanged.

2. .check_govids_in_scope() message reworded. The old text led with
   'v0.1 covers gov_types 0-3' which falsely implied the missing govids
   were scope-excluded types when the more common real cause is a typo
   or a guessed value. New message leads with typo + pre-2017 PID,
   mentions scope exclusion as one possibility, and points at
   cog_gov_search() as the recovery path.

Tests: 165 pass / 0 fail. check 0E/0W/0N.

tests/testthat/test-spending.R

@@ -92,6 +92,27 @@ test_that("cog_spending result has provenance attribute matching schema", {
 })
 
 test_that("cog_spending rejects invalid inputs", {
-  expect_error(cog_spending(123, 2020L), "character")
+  expect_error(cog_spending(list(), 2020L), "character|data frame")
   expect_error(cog_spending("101006006", "2020"), "years")
 })
+
+test_that("cog_spending accepts a cog_gov_search result directly", {
+  skip_if_no_corpus()
+  picks <- cog_gov_search("^BROWARD COUNTY$", state = "FL", type = "county")
+  expect_gt(nrow(picks), 0L)
+  r <- cog_spending(picks, 2020L, "Corrections")
+  expect_equal(unique(r$canonical_govid), "101006006")
+})
+
+test_that("cog_spending accepts a cog_find_peers result directly", {
+  skip_if_no_corpus()
+  peers <- cog_find_peers("101006006", max_peers = 3L)
+  r <- cog_spending(peers, 2020L, "Police")
+  expect_setequal(unique(r$canonical_govid),
+                  sort(peers$canonical_govid))
+})
+
+test_that("cog_spending rejects data.frame without canonical_govid column", {
+  bad <- tibble::tibble(foo = "bar")
+  expect_error(cog_spending(bad, 2020L), "canonical_govid")
+})