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/file.surql

@@ -0,0 +1,18 @@
+# Defines the schema for the 'file' table (used by FileInfo).
+
+DEFINE TABLE IF NOT EXISTS file SCHEMALESS;
+
+# Standard fields
+DEFINE FIELD IF NOT EXISTS created_at ON file TYPE datetime;
+DEFINE FIELD IF NOT EXISTS updated_at ON file TYPE datetime;
+
+# Custom fields from the FileInfo struct
+DEFINE FIELD IF NOT EXISTS sha256 ON file TYPE string;
+DEFINE FIELD IF NOT EXISTS path ON file TYPE string;
+DEFINE FIELD IF NOT EXISTS file_name ON file TYPE string;
+DEFINE FIELD IF NOT EXISTS mime_type ON file TYPE string;
+DEFINE FIELD IF NOT EXISTS user_id ON file TYPE string;
+
+# Indexes based on usage (get_by_sha scoped by user_id, user lookups)
+DEFINE INDEX IF NOT EXISTS file_user_sha256_idx ON file FIELDS user_id, sha256 UNIQUE;
+DEFINE INDEX IF NOT EXISTS file_user_id_idx ON file FIELDS user_id;