feat(stovepipe): add request history table

stovepipe/extension/storage/mysql/schema/request_history.sql

@@ -0,0 +1,18 @@
+-- request_history retains one append-only row per logical request occurrence. Exactly one of
+-- state and event is populated; the remaining sparse columns carry the bounded context required
+-- by that occurrence.
+CREATE TABLE IF NOT EXISTS request_history (
+    queue                     VARCHAR(255) NOT NULL,
+    request_id                VARCHAR(255) NOT NULL,
+    entry_id                  VARCHAR(255) NOT NULL,
+    timestamp_ms              BIGINT         NOT NULL,
+    state                     VARCHAR(64)     NOT NULL DEFAULT '',
+    event                     VARCHAR(64)     NOT NULL DEFAULT '',
+    request_version           INT             NOT NULL DEFAULT 0,
+    superseded_by_request_id  VARCHAR(255) NOT NULL DEFAULT '',
+    build_id                  VARCHAR(255) NOT NULL DEFAULT '',
+    outcome_reason            VARCHAR(64)     NOT NULL DEFAULT '',
+    fact_degree               DOUBLE          NOT NULL DEFAULT 0,
+    PRIMARY KEY (queue, request_id, entry_id),
+    KEY idx_request_history_order (queue, request_id, timestamp_ms, entry_id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

test/integration/stovepipe/extension/storage/mysql/storage_test.go

@@ -100,6 +100,7 @@ func resetStorage(t *testing.T, db *sql.DB) {
 	t.Helper()
 
 	for _, statement := range []string{
+		"TRUNCATE TABLE request_history",
 		"TRUNCATE TABLE request_uri",
 		"TRUNCATE TABLE request",
 		"TRUNCATE TABLE build",