moving ECB to a separate proto file

common/proto/ecb.proto

@@ -0,0 +1,67 @@
+syntax = "proto3";
+
+package komp_ac.ecb;
+
+// Read-only access to ECB conversion audit evidence.
+//
+// This service exists for manual visual verification. It exposes conversions
+// already recorded by backend posting workflows and never recalculates money.
+service EcbService {
+  // List immutable ECB conversion evidence for one money value.
+  rpc ListEcbConversionEvidence(ListEcbConversionEvidenceRequest)
+      returns (ListEcbConversionEvidenceResponse);
+}
+
+// Identify one logical money cell whose conversion history should be inspected.
+message ListEcbConversionEvidenceRequest {
+  // Required. Profile containing the table.
+  string profile_name = 1;
+
+  // Required. Logical table name within the profile.
+  string table_name = 2;
+
+  // Required. Dynamic table row id.
+  int64 record_id = 3;
+
+  // Required. Current display name of the money column. The server resolves it
+  // to the stable physical column name used by immutable evidence.
+  string column_name = 4;
+
+  // Optional. Maximum rows to return. Zero uses 100; maximum is 500.
+  int32 limit = 5;
+
+  // Optional cursor. Return evidence ids lower than this value.
+  optional int64 before_evidence_id = 6;
+}
+
+// One immutable explanation of how a posted EUR value was determined.
+message EcbConversionEvidence {
+  int64 evidence_id = 1;
+  string original_amount = 2;
+  string original_currency = 3;
+  string eur_amount = 4;
+  string conversion_context = 5;
+  string anchor_date = 6;
+  string determination_method = 7;
+  string rounding_method = 8;
+  optional string rate_date = 9;
+  optional string units_per_eur = 10;
+  optional int64 rate_observation_id = 11;
+  optional string observation_hash = 12;
+  optional string source_payload_hash = 13;
+  optional string rate_fetched_at = 14;
+  optional int64 import_batch_id = 15;
+  optional string source_endpoint = 16;
+  string evidence_created_at = 17;
+}
+
+message ListEcbConversionEvidenceResponse {
+  // True when at least one evidence row for this cell used an ECB rate.
+  bool has_exchange = 1;
+
+  // Newest-first immutable history for this page.
+  repeated EcbConversionEvidence evidence = 2;
+
+  // True when another page exists using the last evidence_id as the cursor.
+  bool has_more = 3;
+}