Batch Analyse requests and survive opaque provider schema budgets

Analyse now classifies up to ten same-kind transactions per provider
request: the registry and history travel once per batch, so a
thousand-row backfill costs about a hundred paced requests instead of a
thousand. The answer schema appears once — an array item carrying an
enum-bound ref — because providers meter strict schemas by token cost:
duplicating registry enums per row, or bounding arrays with
minItems/maxItems that Gemini expands per element, rejects real
registries with a bare HTTP 400. Row count, duplicate refs, duplicate
tags and taxonomy bounds are all enforced server-side instead, and a
request still rejected outright halves until accepted, remembering the
working size for the run. Batch requests scale the HTTP budget by row
count, chunk failures cannot abort a run whose later rows succeeded,
and rows resolved against one snapshot share one minted merchant.

Measured on a real 165-row month over a zero-data-retention route:
165 analysed, 152 proposals, 0 errors, 17 requests, under 8 minutes.

Fresh installs default to google/gemini-3.8-flash, the model that
demonstrably honors strict structured outputs over a ZDR route. Preview
changes now carry counterparty, amount and currency, and the review
list shows the amount with a counterparty fallback for banks that leave
descriptions empty.

internal/classification/ledger_test.go

@@ -59,13 +59,14 @@ func ledgerFixture() (domain.Dataset, domain.Facts) {
 	return d, facts
 }
 
-// strictKeywords is what OpenAI-family strict structured-output mode accepts.
-// uniqueItems is specifically rejected ("'uniqueItems' is not permitted") and
-// took every zero-data-retention route for those models down with HTTP 400;
-// duplicates are rejected server-side by decodeAnswer instead.
+// strictKeywords is what every targeted provider accepts in strict
+// structured-output mode. uniqueItems is rejected outright by OpenAI-family
+// endpoints ("'uniqueItems' is not permitted"); minItems/maxItems make Gemini
+// expand array item schemas per element and reject real registries with a
+// bare HTTP 400. Counts and duplicates are enforced server-side instead.
 var strictKeywords = map[string]bool{
 	"type": true, "properties": true, "required": true, "additionalProperties": true,
-	"items": true, "enum": true, "maxItems": true, "maxLength": true, "minLength": true,
+	"items": true, "enum": true, "maxLength": true, "minLength": true,
 }
 
 func checkStrict(t *testing.T, path string, value any) {
@@ -92,6 +93,7 @@ func TestWireSchemasUseOnlyStrictModeKeywords(t *testing.T) {
 	set := retrieve(facts.RawDescription, "expense", d, nil, nil)
 	for name, schema := range map[string]map[string]any{
 		"classification": set.schema(),
+		"batch":          set.batchSchema([]string{"r1", "r2", "r3"}),
 		"taxonomy":       taxonomySchema(),
 		"csv":            csvMappingSchema(CSVMappingRequest{Headers: []string{"Buchung", "Betrag"}}),
 	} {