Add minimal compilation smoke test; tidy go.mod

Add a smoke test that references the package's exported surface so go
test fails if it stops compiling. Run go mod tidy to promote cobra to
a direct dependency.

go.mod

@@ -3,6 +3,7 @@ module git.eeqj.de/sneak/bsdaily
 go 1.26.4
 
 require (
+	github.com/spf13/cobra v1.10.2
 	golang.org/x/sys v0.41.0
 	modernc.org/sqlite v1.44.3
 )
@@ -14,7 +15,6 @@ require (
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/ncruces/go-strftime v1.0.0 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
-	github.com/spf13/cobra v1.10.2 // indirect
 	github.com/spf13/pflag v1.0.9 // indirect
 	golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 // indirect
 	modernc.org/libc v1.67.6 // indirect

internal/bsdaily/bsdaily_test.go

@@ -0,0 +1,21 @@
+package bsdaily
+
+import "testing"
+
+// TestCompiles is a minimal smoke test that references the package's exported
+// surface so that `go test` fails if the package stops compiling. It does not
+// touch the filesystem or any of the hard-coded production paths.
+func TestCompiles(t *testing.T) {
+	if DBFilename == "" || WALFilename == "" || SHMFilename == "" {
+		t.Fatal("expected database filename constants to be set")
+	}
+	if SnapshotBase == "" || TmpBase == "" || DailiesBase == "" {
+		t.Fatal("expected base path constants to be set")
+	}
+	if MinTmpFreeBytes == 0 || MinDailiesFreeBytes == 0 {
+		t.Fatal("expected free-space thresholds to be set")
+	}
+	if ErrNoPosts == nil {
+		t.Fatal("expected ErrNoPosts sentinel to be set")
+	}
+}