Add initial stub for sqlite job archive backend

pkg/archive/migrations/01_init-schema.up.sql

@@ -0,0 +1,9 @@
+CREATE TABLE IF NOT EXISTS "job" (
+    id INTEGER PRIMARY KEY,
+    clustername TEXT NOT NULL,
+    job_id INTEGER NOT NULL,
+    start_time INTEGER NOT NULL, -- Unix timestamp
+    meta_data TEXT,          -- JSON
+    metric_data BLOB,
+    UNIQUE ("job_id", "clustername", "start_time")
+);