fix: resolve all golangci-lint errors (#699)

Fix 12 linting issues that were causing CI failures:

errcheck (8 fixes):
- cmd/bd/mol_burn.go: wrap wispStore.Close() in defer func
- cmd/bd/mol_burn.go: handle fmt.Scanln() return value
- cmd/bd/mol_squash.go: wrap wispStore.Close() in defer func (2 locations)
- cmd/bd/wisp.go: wrap wispStore.Close() in defer func (3 locations)
- internal/beads/beads.go: wrap mainStore.Close() and wispStore.Close()

gosec G104 (2 fixes):
- internal/storage/sqlite/multirepo.go: handle rows.Close() errors

misspell (1 fix):
- cmd/bd/mol_burn.go: change "Cancelled" to "Canceled"

unparam (1 fix):
- cmd/bd/mol_squash.go: use blank identifier for unused cmd parameter

All fixes follow existing patterns in the codebase:
- defer func() { _ = store.Close() }() for deferred closes
- _ = rows.Close() for explicit closes with ignored errors
- _, _ = fmt.Scanln() for ignored return values

Co-authored-by: Charles P. Cross <cpdata@users.noreply.github.com>

cmd/bd/mol_burn.go

@@ -91,7 +91,7 @@ func runMolBurn(cmd *cobra.Command, args []string) {
 		fmt.Fprintf(os.Stderr, "Error opening wisp storage: %v\n", err)
 		os.Exit(1)
 	}
-	defer wispStore.Close()
+	defer func() { _ = wispStore.Close() }()
 
 	// Resolve molecule ID in wisp storage
 	resolvedID, err := utils.ResolvePartialID(ctx, wispStore, moleculeID)
@@ -140,9 +140,9 @@ func runMolBurn(cmd *cobra.Command, args []string) {
 		fmt.Printf("\nContinue? [y/N] ")
 
 		var response string
-		fmt.Scanln(&response)
+		_, _ = fmt.Scanln(&response)
 		if response != "y" && response != "Y" {
-			fmt.Println("Cancelled.")
+			fmt.Println("Canceled.")
 			return
 		}
 	}