adapter-sqlite: all repo implementations + wire fn + migrations copy

migrations_sqlite/20260315000000_add_transcode_settings.sql

@@ -0,0 +1,5 @@
+CREATE TABLE IF NOT EXISTS transcode_settings (
+    id INTEGER PRIMARY KEY CHECK (id = 1),
+    cleanup_ttl_hours INTEGER NOT NULL DEFAULT 24
+);
+INSERT OR IGNORE INTO transcode_settings (id, cleanup_ttl_hours) VALUES (1, 24);