chore: harden common storage bootstrap and slim embedded db assets

Unify embedding config, build providers from system settings, and fail
startup when index builds error or time out. Move Surreal assets under
common/db so embeds exclude crate source, and read storage via streams.

common/db/schemas/ingestion_task.surql

@@ -0,0 +1,16 @@
+# Defines the schema for the 'ingestion_task' table (used by IngestionTask).
+
+DEFINE TABLE IF NOT EXISTS ingestion_task SCHEMALESS;
+
+# Standard fields
+DEFINE FIELD IF NOT EXISTS created_at ON ingestion_task TYPE datetime;
+DEFINE FIELD IF NOT EXISTS updated_at ON ingestion_task TYPE datetime;
+
+DEFINE FIELD IF NOT EXISTS content ON ingestion_task TYPE object;
+DEFINE FIELD IF NOT EXISTS status ON ingestion_task TYPE object;
+DEFINE FIELD IF NOT EXISTS user_id ON ingestion_task TYPE string;
+
+# Indexes explicitly defined in build_indexes and useful for get_unfinished_tasks
+DEFINE INDEX IF NOT EXISTS idx_ingestion_task_status ON ingestion_task FIELDS status;
+DEFINE INDEX IF NOT EXISTS idx_ingestion_task_user ON ingestion_task FIELDS user_id;
+DEFINE INDEX IF NOT EXISTS idx_ingestion_task_created ON ingestion_task FIELDS created_at;