test(01-foundation-03): add failing tests for storage layer

- Tests for AES-256-GCM encrypt/decrypt roundtrip
- Tests for Argon2id key derivation determinism
- Tests for SQLite open with schema tables
- Tests for SaveFinding/ListFindings with encryption contract
- Tests verify raw BLOB does not contain plaintext key

go.mod

@@ -0,0 +1,22 @@
+module github.com/salvacybersec/keyhunter
+
+go 1.26.1
+
+require github.com/stretchr/testify v1.11.1
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/ncruces/go-strftime v1.0.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	golang.org/x/crypto v0.49.0 // indirect
+	golang.org/x/sys v0.42.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	modernc.org/libc v1.70.0 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.11.0 // indirect
+	modernc.org/sqlite v1.48.1 // indirect
+)