Add support for parsing the flake.lock.

migrations/20260725025954_flake_inputs.down.sql

@@ -0,0 +1,2 @@
+DROP INDEX ix_flake_inputs_build_id;
+DROP TABLE flake_inputs;

migrations/20260725025954_flake_inputs.up.sql

@@ -0,0 +1,9 @@
+CREATE TABLE flake_inputs (
+       id INTEGER NOT NULL PRIMARY KEY,
+       build_id INTEGER NOT NULL,
+       input_name TEXT NOT NULL,
+       rev TEXT NOT NULL,
+       FOREIGN KEY(build_id) REFERENCES build(id)
+) STRICT;
+
+CREATE INDEX ix_flake_inputs_build_id ON flake_inputs(build_id);