Removes code and fixtures nothing uses: the internal/models package and its test, a second SnapshotInfo type in package cli that had no references (the live one is in internal/vaultik), and two config fixtures, test-config.yml and test/integration-config.yml, whose keys the config loader no longer accepts. test/config.yaml stays; a test uses it. Also fixes config set, which rewrote the whole file with 4-space indentation on the first set despite the documented promise to preserve formatting. It now encodes with 2-space indent like the default template, and a test asserts comments and indentation survive a set. Deviation: one commit, not one per deletion as the issue asked. model: claude-opus-4-8 (implementation, review); claude-fable-5-1 (merge)